**EXHIBIT 99.20****RECONCILIATION TO UNITED STATES GAAP****Reconciliation to United States GAAP — Cameco Corporation**The consolidated financial statements of Cameco are expressed in Canadian dollars in accordancewith Canadian generally accepted accounting principles (Canadian GAAP). The followingadjustments and disclosures would be required in order to present these consolidated financialstatements in accordance with accounting principles generally accepted in the United States (USGAAP).**(a)** **Reconciliation of earnings in accordance with Canadian GAAP to earnings determined inaccordance with US GAAP:**            **2007** **2006**          **Net earnings under Canadian GAAP** **$****416,112**  **$****375,715** Add (deduct) adjustments for (d):        Pre-operating costs (i)  1,512   1,512 Stripping costs (ii)  (52,773)  (6,020)Hedges and derivative instruments (iii) (iv)  —   5,668 Earnings from BPLP (iii)  —   (1,003)Tax uncertainties and business combinations (viii)  —   (3,727)Stock-based compensation (ix)  74,179   (3,998)Uncertain tax positions [g (i)]  (2,226)  — Income tax effect of adjustments  (25,033)  (14,258)Minority interest effect of adjustments  22,719   4,326   **Net earnings under US GAAP**  **434,490**   **358,215** Hedges and derivative instruments (iii)  145,640   40,076 Unamortized actuarial gain (x)  23,590   — Unamortized actuarial gain transferred to net earnings (x)  (19,900)  — Foreign currency translation adjustments (v)  (111,169)  13,631 Unrealized loss on available-for-sale securities (vi)  (6,366)  (107)Additional pension obligation (vii)  —   (31,568) **Comprehensive income under US GAAP** **$****466,285**  **$****380,247**  **Basic net earnings per share under US GAAP** **$****1.24**  **$****1.02**  **Diluted earnings per share under US GAAP** **$****1.18**  **$****0.97**  
 

 
**(b)** **Comparison of balance sheet items determined in accordance with Canadian GAAP to balancesheet items determined in accordance with US GAAP:**   **(i)** **Balance Sheets**                    **2007** **2006**  **Canadian** **US** **Canadian** **US**  **GAAP** **GAAP** **GAAP** **GAAP**                  Current assets $1,291,144  $1,108,165  $1,354,424  $1,235,813 Property, plant and equipment [e]  3,437,450   2,786,850   3,198,133   2,589,873 Intangible assets and goodwill  255,484   251,757   294,158   290,431 Long-term receivables, investments and other [e]  387,304   425,478   293,714   348,528  **Total assets** **$****5,371,382**  **$****4,572,250**  **$****5,140,429**  **$****4,464,645**                   Current liabilities $684,464  $490,360  $501,697  $393,803 Long-term debt [e]  717,130   556,295   696,691   529,790 Provision for reclamation  284,673   284,673   228,496   228,496 Other liabilities [e]  258,511   169,959   232,641   160,761 Deferred income taxes  246,936   163,674   339,451   257,508                      2,191,714   1,664,961   1,998,976   1,570,358                  Minority interest  435,807   408,050   400,071   395,745                  Shareholders’ equity                Share capital  819,268   819,268   812,769   812,769 Contributed surplus  119,531   106,563   540,173   507,753 Retained earnings  1,779,629   1,707,899   1,428,206   1,344,331 Accumulated other comprehensive income                — net actuarial loss [d(x)]  —   (178,708)  —   (180,630)— transitional obligation  —   —   —   (165)— prior service cost  —   (2,438)  —   (4,041)— cumulative translation account [d]  (150,935)  (129,713)  (39,766)  (18,545)— hedges and derivative instruments [d(iii)]  182,734   182,734   —   37,070 — available-for-sale securities  (6,366)  (6,366)  —   —  **Total accumulated other comprehensive income**  25,433   (134,491)  (39,766)  (166,311) **Total shareholders’ equity**  2,743,861   2,499,239   2,741,382   2,498,542  **Total liabilities and shareholders’ equity** **$****5,371,382**  **$****4,572,250**  **$****5,140,429**  **$****4,464,645**  **(ii)** **Components of accounts payable and accrued liabilities are as follows:**** **** **                 Accounts payable $265,331  $204,087  $273,784  $188,733 Taxes and royalties payable  103,703   103,703   65,834   65,834 Accrued liabilities  172,249   74,836   53,061   53,061  **Total accounts payable and accrued liabilities** **$****541,283**  **$****382,626**  **$****392,679**  **$****307,628**  
 

 
**(c)** **The effects of these adjustments would result in the consolidated statements of cashflows reporting the following under US GAAP:**            **2007** **2006** Cash provided by operations $713,996  $398,100 Cash used in investing $(446,184) $(495,378)Cash used in financing $(429,129) $(175,602) **(d)** **A description of certain significant differences between Canadian GAAP and US GAAP follows:**  **(i)** **Pre-Operating Costs**    Under Canadian GAAP, pre-operating costs incurred during the commissioning phase of anew project are deferred until commercial production levels are achieved, subject totime limitations. Under US GAAP, such costs are expensed as incurred as required byAICPA Statement of Position 98-5, Reporting on the Cost of Start-Up Activities.McArthur River commercial production commenced March 1, 2000 for US GAAP and November1, 2000 for Canadian GAAP. Differences in capitalized costs are amortized over theestimated lives of the assets to which they relate.  **(ii)** **Stripping Costs**    Under Canadian GAAP, stripping costs incurred during the production phase by miningcompanies to remove overburden and other mine waste materials in order to accessmineral deposits, can be either expensed or capitalized given the specifics of thesituation. Under US GAAP, stripping costs are deemed to be variable production coststhat should be included in the costs of the inventory produced during the period thatthe stripping costs are incurred. Stripping costs of $53,740,000 were incurred in 2007(2006 — $6,020,000) and capitalized at Centerra’s mines under Canadian GAAP. Under USGAAP, adjustments were made to expense these amounts. Differences in capitalized costsare amortized over the estimated lives of the assets to which they relate. In 2007, anadjustment was made to reduce the amount of depreciation charged to earnings by$967,000 (2006 — nil).  **(iii)** **Hedges and Derivative Instruments**    Under US GAAP, all derivative instruments are recognized on the balance sheet as eitherassets or liabilities measured at fair value. Changes in the fair value of derivativesare recognized in earnings unless specific hedge criteria are met to qualify as a cashflow hedge. Changes in the fair value of derivatives that qualify as fair value hedges,are recognized in earnings in the same period as the hedged items. Changes in the fairvalue of the effective portion of a cash flow hedge are deferred in other comprehensiveincome with any ineffectiveness of the hedge recognized immediately on the statement ofearnings. Canadian GAAP related to this matter was amended to be consistent with USGAAP on a prospective basis effective January 1, 2007.    Prior to 2004, forward points were included in the assessment of hedge effectivenessfor Canadian GAAP purposes and excluded for US GAAP purposes. The cumulative impact ofthis difference was $16,042,000 at December 31, 2003, of which $2,173,000 wasrecognized in 2006. At the end of 2006, all differences had been recognized.    For amounts included in the balance sheet as accumulated other comprehensive income asatDecember 31, 2006, a loss of $615,000 (after tax) related to the hedging of foreignexchange risk. The impact on other comprehensive income for 2006 was a loss of$22,497,000.    BPLP also has certain derivative instruments that qualify for hedge accounting. Foramounts included in the balance sheet as accumulated other comprehensive income as atDecember 31, 2006, a gain of $37,685,000 (after tax) related to the hedging ofelectricity price risk. The impact
 

 
 **** on other comprehensive income for hedge accounting for 2006 was a gain of $62,573,000.    Prior to August 2003, certain BPLP energy contracts did not qualify for hedgeaccounting under US GAAP as the documentation required for hedge accounting was notcontemplated at the time of entering into the contracts. Accordingly, changes in thefair value of these contracts were charged to US GAAP earnings. Under Canadian GAAP,hedge accounting was applied prior to August 2003, resulting in differences to berecognized in future periods. As a result of this past difference in hedge accountingtreatment, a loss of $1,003,000 was recognized in 2006. At the end of 2006, alldifferences had been recognized.  **(iv)** **Embedded Derivative Instruments**    Under US GAAP, all derivative instruments are recognized on the balance sheet as eitherassets or liabilities measured at fair value. Prior to 2007, under Canadian GAAP,derivatives embedded within hybrid instruments were not separately accounted for. In2006, certain of Cameco’s sales contracts contained embedded foreign currencyderivatives. As a result they were separately accounted for under US GAAP and$7,841,000 was recognized in earnings in 2006. Canadian GAAP related to this matterwas amended to be consistent with US GAAP on a prospective basis effective January 1,2007.  **(v)** **Cumulative Translation Account**    Under US GAAP, exchange gains and losses arising from the translation of our netinvestments in foreign operations are included in comprehensive income. In addition,exchange gains and losses of any foreign currency debt designated as hedges of thosenet investments are included in comprehensive income. Cumulative amounts are includedin accumulated other comprehensive income on the balance sheet. Canadian GAAP relatedto this matter was amended to be consistent with US GAAP on a prospective basiseffective January 1, 2007.  **(vi)** **Available-for-Sale Securities**    Prior to January 1, 2007, under Canadian GAAP, portfolio investments were accounted forusing the cost method. Under US GAAP, portfolio investments classified asavailable-for-sale securities are carried at market values with unrealized gains orlosses reflected as a separate component of shareholders’ equity and included incomprehensive income. Canadian GAAP related to accounting for these investments wasamended to be consistent with US GAAP on a prospective basis effective January 1, 2007.  **(vii)** **Additional Pension Obligation**    Under US GAAP, for defined benefit pension plans, an unfunded accumulated benefitobligation should be recorded as an additional minimum pension liability. UnderCanadian GAAP there is no requirement to recognize an additional minimum pensionliability. In 2006 for the BPLP benefit plans, the impact on other comprehensiveincome is a loss of $31,568,000. The amount in accumulated other comprehensive incomeat December 31, 2006, was a net actuarial loss of $31,568,000. As a result of theimplementation of Statement No. 158, Employers’ Accounting for Defined Benefit Pensionand Other Post-retirement Plans (“FAS 158”) [note (d) x], there is no requirement todetermine an additional minimum liability for years after 2006.  **(viii)** **Tax Uncertainties and Business Combinations**    Uncertainties related to income taxes may exist at the time of a business combination,which affect the recognition of future income tax assets. These uncertainties mayresult because the realizability of the future income tax asset is uncertain, orbecause the existence of the asset is uncertain.    Under US GAAP, when a future income tax asset acquired in a business combination thatwas not recognized as an identifiable asset by the acquirer at the date of theacquisition (for realizability or
 

 
   existence issues) is subsequently recognized by the acquirer, the benefit should beapplied as follows: 1) first to reduce to zero any goodwill related to the acquisition;2) second to reduce to zero other non-current intangible assets related to theacquisition; 3) third to reduce income tax expense.    Under Canadian GAAP, this approach only applies to tax uncertainties related torealizability. If the tax uncertainty is related to existence, then subsequentadjustments related to the tax uncertainties would be treated as a change inmanagement’s estimates and directly recorded to earnings. In 2006, a tax uncertaintydue to existence was removed related to assets acquired by Centerra from Kyrgyzaltyn in2004 when Centerra acquired an additional 66.7% interest in Kumtor Gold Company. As aresult, a gain of $6,098,000 was recorded to income tax for Canadian GAAP purposes. Anadjustment of $3,727,000 was made to reallocate part of the gain to goodwill for USGAAP purposes.  **(ix)** **Stock-Based Compensation**    Under Canadian GAAP, in accordance with EIC 162 [note 3(b)], Cameco recognizesstock-based compensation expense over the shorter of the period to eligible retirementor the vesting period for stock-based awards granted on or after January 1, 2003.Under US GAAP, this accounting treatment is applied to stock-based awards granted on orafter January 1, 2006. Stock-based awards granted prior to January 1, 2006, arerecognized over the full vesting period of the award. As a result, an adjustment wasmade to increase stock compensation expense by $1,947,000 in 2007 (2006 — $3,998,000).    In 2007, the company amended its stock option program, introducing a cash settlementfeature for the exercise of employee stock options. Under Canadian GAAP, options thatinclude a cash settlement feature are classified as liabilities and carried at theirintrinsic value. The intrinsic value is marked to market each period with anoffsetting adjustment to expense. Under US GAAP, the liabilities are required to beremeasured to their fair value as of the date of the financial statements. For US GAAPpurposes, the fair value of the options was determined using the Black-Scholesoption-pricing model. As a result, compensation expense for 2007 has been reduced by$76,126,000 (2006 — nil).  **(x)** **Pension and Other Post-Retirement Benefits**    In September 2006, the FASB issued Statement No. 158, Employers’ Accounting for DefinedBenefit Pension and Other Post-Retirement Plans, an amendment of FASB Statements No.87, 88, 106 and 132(R). FAS 158 requires an entity to recognize the funded status of abenefit plan in the balance sheet and to recognize the existing unrecognized net gainsand losses, unrecognized prior service costs, and unrecognized net transition assets inother comprehensive income. There is no similar requirement under Canadian GAAP.    For the Cameco benefit plan, the cumulative effect of the change in policy on thebalance sheet at December 31, 2006 was to decrease shareholders’ equity by $4,646,000(net actuarial loss of $4,481,000 and transitional obligation of $165,000), decreaselong-term receivables, investments and other by $6,749,000 and decrease future incometaxes by $2,103,000. For 2007, a loss of $2,696,000 was included in othercomprehensive income.    For the BPLP benefit plan, the cumulative effect of the change in policy on the balancesheet at December 31, 2006 was to decrease shareholders’ equity by $148,622,000 (netactuarial loss of $144,581,000 and prior service cost of $4,041,000), decreaselong-term receivables, investments and other by $215,393,000 and decrease future incometaxes by $66,771,000. For 2007, a gain of $17,101,000 was included in othercomprehensive income.
 

 
   In 2007, the Canadian government enacted amendments to the Canadian Income Tax Act thatprovide for a reduction in the general corporate income tax rate. The cumulativeeffect on the income taxliability related to the aforementioned adjustments for pension and otherpost-retirement benefits was an increase of $10,715,000.**(e)** **Investment in BPLP**   Under Canadian GAAP, Cameco accounts for its interest in BPLP by the proportionateconsolidation method. Under US GAAP, Cameco is required to equity account for itsinvestment and record in earnings its proportionate share of their net earnings measured inaccordance with US GAAP. **(f)** **Convertible Debentures**   Under US GAAP, convertible debentures are to be classified entirely as debt rather thanequity. Due to the difference, accretion related to the equity component of convertibledebentures for Canadian GAAP should be reversed for US GAAP purposes. Since all interestrelated to the debentures is being capitalized under both US and Canadian GAAP, theadjustment only affects the balance sheet. The cumulative effect is to decreaseshareholders’ equity by $30,473,000, increase long-term debt by $19,948,000 and decreaseproperty, plant and equipment by $10,525,000 at December 31, 2007. **(g)** **Changes in Accounting Policy** **(i)** **Accounting for Uncertainty in Income Taxes**    In July 2006, the FASB issued Financial Interpretation No. 48, Accounting forUncertainty in Income Taxes — an interpretation of FASB Statement No. 109 (“FIN 48”).FIN 48 provides additional guidance on how a company is to recognize, measure anddisclose uncertain tax positions that it has taken in its tax filings. Canadian GAAPhas no similar requirements related to uncertain tax positions.    Effective January 1, 2007, Cameco adopted the provisions of FIN 48 and upon adoption,reclassified $16,757,000 from deferred income tax liabilities to current liabilitiesfor income taxes. In addition the company recorded an increase in the liability forunrecognized income tax benefits of $1,604,000 at January 1, 2007. The increase in theliability was offset by corresponding decreases of $892,000 in retained earnings and$712,000 in minority interest.    For 2007 an expense of $2,226,000 has been recognized for changes in uncertain taxpositions with a corresponding $864,000 adjustment to minority interest.**(h)** **Future Changes in Accounting Policy** **(i)** **Framework on Fair Value Measurement**    In September 2006, the FASB issued Statement No. 157, Fair Value Measurements (“FAS157”). FAS 157 defines fair value, establishes a framework for measuring fair value inGAAP and expands disclosures about fair value measurements. FAS 157 will be effectivefor financial statements issued for fiscal years beginning after November 15, 2007.However, certain elements of the standard related to non-financial assets andliabilities have been deferred to fiscal years beginning on or after November 15, 2008.Cameco does not expect the adoption of this statement will have a material impact onits consolidated financial statements.  **(ii)** **Fair Value Option for Financial Assets and Liabilities**    In February 2007, the FASB issued Statement No. 159, The Fair Value Option forFinancial Assets and Liabilities (“FAS 159”). FAS 159 provides an entity the option tomeasure many financial instruments and certain other items at fair value that are nototherwise currently required. FAS 159 also establishes presentation and disclosurerequirements for assets and liabilities measured at fair value in an effort to allowcomparisons between entities that choose alternative 
 

 
   methods. Cameco does not expectthe adoption of this statement will have a material impact on its consolidatedfinancials statements. **(iii)** **Noncontrolling Interests in Consolidated Financial Statements**    In December 2007, the FASB issued Statement No. 160, Noncontrolling Interests inConsolidated Financial Statements (“FAS 160”). FAS 160 specifies that noncontrollinginterests be treated as a separate component of equity, not as a liability or otheritem outside of equity. FAS 160 is effective for periods beginning on or after December15, 2008 and will be applied prospectively to all noncontrolling interests, includingany that arose before the effective date. Cameco does not expect the adoption of thisstatement will have a material impact on its consolidated financial statements.  **(iv)** **Business Combinations**    In December 2007, the FASB issued a revised standard on accounting for businesscombinations, Statement No. 141(R), Business Combinations (“FAS 141(R)”). FAS 141(R)specifies a number of changes including: an expanded definition of a business, arequirement to measure all business acquisitions at fair value, a requirement tomeasure noncontrolling interests at fair value and a requirement to recognizeacquisition-related costs as expenses. FAS 141R is applicable to business combinationsoccurring after December 15, 2008.**AUDITORS’ REPORT ON RECONCILIATION TO UNITED STATES GAAP**To the Board of Directors of Cameco CorporationOn February 27, 2008, we reported on the consolidated balance sheets of Cameco Corporation as atDecember 31, 2007 and 2006 and the consolidated statements of earnings, shareholders’ equity,comprehensive income and cash flows for the years then ended which are included in the annualreport on Form 40-F. In connection with our audits of the aforementioned consolidated financialstatements, we also have audited the related supplemental note entitled “Reconciliation to UnitedStates GAAP “ included in the Form 40-F. This supplemental note is the responsibility of thecorporation’s management. Our responsibility is to express an opinion on this supplemental notebased on our audits.In our opinion, such supplemental note, when considered in relation to the basic consolidatedfinancial statements taken as a whole, presents fairly, in all material respects, the informationset forth therein./s/ KPMGLLPChartered AccountantsSaskatoon, CanadaFebruary 27, 2008
 

 
**COMMENTS BY AUDITORS FOR US READERS ON CANADA — US REPORTING DIFFERENCES**To the Board of Directors of Cameco CorporationIn the United States, reporting standards for auditors require the addition of an explanatoryparagraph (following the opinion paragraph): **•** that refers to the audit report on the corporation’s internal control over financialreporting. Our report to the shareholders dated February 27, 2008 is expressed inaccordance with Canadian reporting standards, which do not require a reference to theauditors’ report on the corporation’s internal control over financial reporting in theauditors’ report on the consolidated financial statements.  **•** when there is a change in accounting principles that has a material effect on thecomparability of the corporation’s financial statements such as the changes described innote 3 to the consolidated financial statements. Our report to the shareholders datedFebruary 27, 2008 is expressed in accordance with Canadian reporting standards, which donot require a reference to changes in accounting principles in the auditors’ report whenthe change is properly accounted for and adequately disclosed in the financial statements./s/ KPMGLLPChartered AccountantsSaskatoon, CanadaFebruary 27, 2008