As filed with the Securities and Exchange Commission on September 27, 2010.







Form 20-F/A

(Mark One)



| ̈ | REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ----------------------------------------------------------------------------------------------

OR



|x | ANNUAL REPORT PURSUANT TO SECTION 13 OR l5(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ------------------------------------------------------------------------------------

For the year ended December 31, 2009

OR



| ̈ | TRANSITION REPORT PURSUANT TO SECTION 13 OR l5(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ----------------------------------------------------------------------------------------

Commission file number 1-10284





Allied Irish Banks,

public limited company



(Exact name of registrant as
specified in its charter)





Ireland



(Jurisdiction of incorporation or organization)

Bankcentre, Ballsbridge, Dublin 4, Ireland



(Address of principal executive
offices)

David OCallaghan, Company Secretary

Allied Irish Banks, p.l.c.

Bankcentre, Ballsbridge

Dublin 4, Ireland

Telephone no: +353 1 6600311



(Name, telephone number and
address of Company contact person)



Securities
registered or to be registered pursuant to Section 12(b) of the Act



|                                                                            |  |  |  |                                          
|--------------------------------------------------------------------------- |  |  |  | -----------------------------------------
|Title of each class                                                         |  |  |  | Name of each exchange
on which registered
|                                                                            |  | 
|Ordinary shares of EUR 0.32 each, represented
by American Depositary Shares |  |  |  | New York Stock Exchange                  

Securities registered or to be registered pursuant to Section 12(g) of the Act.

None

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act.

None

Indicate the
number of outstanding shares of each of the issuers classes of capital or common stock as of the close of the period covered by the annual report.



|                                 |  |            
|-------------------------------- |  | -----------
|Ordinary shares of EUR 0.32 each |  | 918,435,570

Indicate by check mark
if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.  x Yes   ̈ No

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the
Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90
days.  x Yes   ̈ No

Indicate by check mark whether the registrant is a large accelerated filer, an acceleratted filer, or a non-accelerated filer. See definition of
accelerated filer and large accelerated filer in Rule 12b-2 of the Exchange Act.

Large accelerated
filer  x                Accelerated
filer   ̈                Non-accelerated
filer   ̈

Indicate by check mark which basis of accounting the
registrant has used to prepare the financial statements included in this filing:

US GAAP   ̈         
       IFRS  x                Other  
 ̈

If Other has been checked in response to the previous question,
indicate by check mark which financial statement item the registrant has elected to
follow.   ̈ Item 17   ̈ Item 18

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange
Act).   ̈ Yes  x No









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EXPLANATORY NOTE

Allied Irish Banks, p.l.c. is filing this amendment on Form 20-F/A to its Annual Report on Form 20-F for the fiscal year ended December 31,
2009, which was originally filed with the Securities and Exchange Commission on March 8, 2010, to file certain additional Exhibits required by Item 19.

This Form 20-F/A consists of a cover page, this explanatory note, the Exhibit Index, the signature page and the Exhibits. Other than as expressly
set forth above, this Form 20-F/A does not, and does not purport to, amend, update or restate the information in any other Item of the Form 20-F or reflect any events that have occurred after the Form 20-F was filed.



1



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LOGO



EXHIBIT INDEX



|               |  |                                                                                                                                                                          
|-------------- |  | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Exhibit
Number |  | Description of Exhibit                                                                                                                                                   
|               | 
|1.1            |  | Memorandum & Articles of Association (including special resolutions AGM 13 May 2009)                                                                                     
|               | 
|4.1            |  | CIFS Scheme Guarantee Acceptance Deed  Allied Irish Banks, p.l.c.                                                                                                       
|               | 
|4.2            |  | CIFS Scheme Guarantee Acceptance Deed  AIB Bank (CI) Ltd                                                                                                                
|               | 
|4.3            |  | CIFS Scheme Guarantee Acceptance Deed  AIB Group (UK) plc                                                                                                               
|               | 
|4.4            |  | CIFS Scheme Guarantee Acceptance Deed  Allied Irish Banks North America Inc                                                                                             
|               | 
|4.5            |  | CIFS Scheme Guarantee Acceptance Deed  AIB Mortgage Bank                                                                                                                
|               | 
|4.6            |  | ELG Scheme Guarantee Scheme Agreement  Allied Irish Banks, p.l.c.                                                                                                       
|               | 
|4.7            |  | ELG Scheme Guarantee Scheme Agreement  AIB Bank (CI) Ltd                                                                                                                
|               | 
|4.8            |  | ELG Scheme Guarantee Scheme Agreement  AIB Group (UK) plc                                                                                                               
|               | 
|4.9            |  | ELG Scheme Guarantee Scheme Agreement  Allied Irish Banks North America Inc                                                                                             
|               | 
|4.10           |  | Warrant Instrument                                                                                                                                                       
|               | 
|4.11           |  | NPRFC Subscription
Agreement*                                                                                                                                            
|               | 
|4.12           |  | Share Purchase Agreement dated 10 September 2010 among Allied Irish Banks, p.l.c., AIB European Investments Limited, AIB Capital Markets, p.l.c. and Banco Santander
S.A.
|               | 
|8.1            |  | Subsidiaries List                                                                                                                                                        
|               | 
|12.1           |  | Certification of Group Chief Financial Officer                                                                                                                           
|               | 
|12.2           |  | Certification of Group Managing Director                                                                                                                                 
|               | 
|15.1           |  | Special resolutions  EGM 23 December 2009                                                                                                                               
|               | 
|15.2           |  | Special resolutions  AGM 28 April 2010                                                                                                                                  



|* | Confidential treatment has been requested. Confidential materials have been reducted and separately filed with the SEC.
|- | -----------------------------------------------------------------------------------------------------------------------



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SIGNATURES

The registrant hereby certifies that it meets all of the requirements for filing on Form 20-F and that it has duly caused and authorized the
undersigned to sign this Amendment to its annual report on its behalf.



|                        |  |                              
|----------------------- |  | -----------------------------
|Date: 27 September 2010
|                        | 
|Signature:              |  | /s/    Bernard Byrne         
|Name:                   |  | Bernard Byrne                
|Title:                  |  | Group Chief Financial Officer