UK National Health Service IT director Richard Granger has announced he will quit his post by the end of the year.
Granger heads NHS Connecting for Health, which runs the health service's £12.4bn National Programme for IT (NPfIT).
He will move to work "primarily in the private sector" next year and said he was considering several approaches from would-be employers.
NPfIT, the world's largest IT project, has come under critical scrutiny from MPs. In April, the powerful Commons public accounts committee warned that NPfIT was unlikely to deliver significant benefits to the treatment of patients by the end of its 10-year contract, unless there was a fundamental change in the rate of progress on the project. Last week, Granger sharply rebuked critics of the NHS IT revamp, saying a withdrawal of funding would lead to a "massive disruption" for patients.
The MPs said: "The Department [of Health] is unlikely to complete the Programme anywhere near its original schedule." Four years after NPfIT's start, there was still uncertainty "about the costs of the Programme for the local NHS and the value of the benefits it should achieve", they added.
The committee warned that if the project failed, "it could set back IT developments in the NHS for years, and divert money and staff time from front line patient services".
But announcing his intention to leave, Granger said: "My decision should be seen in the context of the changing role of the centre of the NHS and the fact that when I took on this challenge I said I would give this job five years."
He added: "There remain a number of challenges ahead, but I firmly believe that the leadership of the programme by [health minister] Lord Hunt, [NHS chief executive] David Nicholson and my colleagues within CfH will ensure these hurdles are overcome."
Granger, who is known for his combative style and recently hit out at "whining" critics, said he was "proud of what has been achieved" by the team he established following his appointment in October 2002.
"I passionately believe that the programme will deliver ever greater levels of benefit to patients over the coming years. I want to acknowledge the enduring professional support I have received from my team and colleagues throughout the NHS."
The NHS IT chief appeared before MPs at a hearing of the Commons health select committee last week and pledged that the long-delayed Lorenzo care record system at the heart of NPfIT would start to be rolled out next year.
His announcement means he will no longer be in post by that time. Delivery of the software, produced by troubled supplier iSoft is already running more than two years late.
Granger has previously worked as a partner at Deloitte Consulting, having spent his early career at Anderson Consulting, now Accenture - a lead contractor on NPfIT until its pull-out last year.
He has worked on major IT projects both in the UK and Eastern Europe, and led the project management and system integration of London's congestion charging scheme.