Onex Completes Sale of Emergency Medical Services for 8 Times Cost

All amounts in U.S. dollars unless otherwise stated 

Toronto, May 25, 2011 – Onex Corporation ("Onex") (TSX: OCX) today announced it has completed the sale of Emergency Medical Services Corporation (“EMSC”) to an affiliate of Clayton, Dubilier & Rice LLC for $64 in cash for each share. 

In 2005, Onex, Onex Partners I and certain co-investors invested $214 million in EMSC and have now received proceeds of $1.66 billion. This results in a multiple of invested capital of approximately 8 times and an IRR of 47%. Onex’ portion of these proceeds is $639 million including $51 million in carried interest. 

“EMSC has been an excellent investment for Onex’ shareholders and limited partners,” said Robert Le Blanc, Managing Director of Onex. “William Sanger and his first-class management team have been tremendous partners and we look forward to following their ongoing success.” 

About Onex 
Onex is one of North America’s oldest and most successful investment firms committed to acquiring and building high-quality businesses in partnership with talented management teams. Onex manages investment platforms focused on private equity, credit securities and real estate. In total, the company manages approximately $15 billion, of which $10 billion is third-party capital. As well, Onex invests its own capital directly and as a substantial limited partner in each of its Funds. 

Onex’ businesses generate annual revenues of $35 billion, have assets of $40 billion and employ approximately 212,000 people worldwide. Onex shares trade on the Toronto Stock Exchange under the stock symbol OCX. For more information on Onex, visit its website at www.onex.com. The Company’s security filings can also be accessed atwww.sedar.com.  

Forward-Looking Statements 
This news release may contain forward-looking statements that are based on management’s current expectations and are subject to known and unknown uncertainties and risks, which could cause actual results to differ materially from those contemplated or implied by such forward-looking statements. Onex is under no obligation to update any forward-looking statements contained herein should material facts change due to new information, future events or otherwise.