Aon plc — Director's Dealing 2010

May 18, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AON CORP (AOC)
CIK: 0000315293
Period of Report: 2010-05-15

Reporting Person: McGill Stephen P (Chairman/CEO - ARS)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-05-15	Common Stock	M	13750	—	Acquired	80169	Direct
2010-05-15	Common Stock	F	5425	$41.61	Disposed	74744	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2010-05-15	Restricted Stock Unit Award (Right to Receive)	$	M	13750	Disposed	2010-05-15	Common Stock (13750)	Direct

Footnotes

F1: Shares of common stock acquired upon the vesting of a restricted stock unit award.

F2: Shares of common stock withheld by the issuer for the payment of withholding taxes in connection with the vesting of a restricted stock unit award.

F3: The restricted stock unit award converts to shares of common stock on a 1-for-1 basis.