Exhibit 4.18
  United States Annex to the Rules of the Rio Tinto 2008 Bonus Deferral Plan
     1.
    
    Except as otherwise may be indicated, the Definitions contained in the Plan shall apply to
this Annex.2.
    
    Rule 4.2.1 of the Plan shall not apply to US Participants, and the following text shall
instead apply to US Participants:
 4.2.1 If a Participant ceases to be an employee of any Member of the Group prior to the
Vesting Date for any of the reasons set out below, then i) the Bonus Deferral Award will
Vest with no pro rata reduction and ii) any Company Contributed Award will Vest pro rata
based on service from 1 January 2009 to the date that employment ceases as a proportion of
the total possible service applicable to the Award or portion of the Award from 1 January
2009 to the applicable Vesting Date. The reasons are:
 (i)
    
    Disability;(ii)
    
    retirement;(iii)
    
    the Participants employing company ceasing to be under the Control of
the Company;(iv)
    
    a transfer of the undertaking, or the part of the undertaking, in which
the Participant works to a person which is neither under the Control of the
Company nor a Member of the Group or the Other Listed Group;(v)
    
    Involuntary separation from service; or(vi)
    
    Death.
 - 1 -




---



##### 



For the purposes of the foregoing:(1) Group (in addition to the definition in the Plan) shall include any entity included
with the Company in a controlled group of corporations or trades or businesses under common
control within the meaning of U.S. Internal Revenue Code §414(b) or §414(c), an affiliated
service group within the meaning of Code §414(n), or any other entity required to be
aggregated with the Company under Code §414(o); for all purposes under this Plan, in
applying Code §1563(a)(1), (2) and (3) for purposes of determining the Companys affiliates
under Code §414(b), the language at least 80% shall be applied as it appears in those
sections, and in applying U.S. Treas. Reg. §1.414(c)-2 for purposes of determining trades
or business (whether or not incorporated) that are under common control for purposes of
Code §414(c), the language at least 80% shall be used as it appears in such regulation.(2) Disability means the Participant is unable to engage in any substantial gainful
activity by reason of any medically determinable physical or mental impairment that can be
expected to result in death or can be expected to last for a continuous period of not less
than 12 months; the Participant is, by reason of any medically determinable physical or
mental impairment that can be expected to result in death or can be expected to last for a
continuous period of not less than 12 months, receiving income replacement benefits for a
period of not less than three months under an accident and health plan covering employees
of some or all of the Group, or the Participant is determined to be totally disabled by
the U.S. Social Security Administration.(3) Involuntary separation from service occurs as of a specified date if the facts and
circumstances indicate, because the Participants employment is terminated for reasons
other than cause, that (1) the Participant will perform no further services after that date
for the Group, or (2) the level of bona fide services that the Participant would perform
after that date would permanently decrease to 20% or less of the average level of bona fide
services over the immediately preceding 36-month period (or the full period of such
services, if less than 36 months).Any portion of an Award that does not Vest in accordance with this rule shall lapse and for
the avoidance of doubt Rule 1.5 (Dividend Equivalent) shall only apply to the portion that
has Vested.Where a Participants employment is transferred to the Other Listed Group prior to Vesting,
Rule 7.3 (Other Listed Group) will apply.
 3.
    
    Except as modified by the terms of this Annex for US Participants, the Plan remains in full
force and effect.
  - 2 -