Summary Head of Microsoft's Windows division Steven Sinofsky has left the company with immediate effect.
His departure comes just weeks after Microsoft launched Windows 8, the latest edition of its flagship product, seen as key to the firm s future.
Microsoft did not give any reason for Mr Sinofsky s departure.
The company said Julie Larson-Green would be promoted to lead all Windows software and hardware engineering.
He added that many observers saw Mr Sinofsky as a potential successor to Steve Ballmer, Microsoft s chief executive.
Mr Sinofksy s departure is the latest change at the top of some of the world s biggest technology companies.
Last month, Apple announced that Scott Forstall, head of its iOS software, and John Browett, head of retail, would be leaving the firm.
The announcement followed problems with Apple s new mapping software and disappointing quarterly results.
Meanwhile, Yahoo - which has been trying to regain some of its lost market share - also hired a new chief operating officer in October.
In July the internet company appointed its third chief executive in a year.
Microsoft s Mr Ballmer said the changes in leadership were aimed at ensuring the firm continued to be a dominant player in the sector.
