Apple Australia's managing director is quitting due to ill health.

Diana Ryall is leaving Apple after 20 years' service. She joined as a part-time instructor in Sydney, a move that took her on a 17-year ride to the top. Apple Australia was was Australia's Employer of the Year for 2000, with Ryall at the helm.

Ryall – who was diagnosed with cancer last year – told IT magazine: "I'm going to miss Apple like crazy, I'm going to miss the people".

However, the pressure of increasing Apple's market share and this year's collapse of retail venture Buzzle – leaving a $25 million debt – have taken their toll.

Ryall fell into the world of computers. After graduating in maths and statistics in Sydney, she moved to Canada, and then back to Australia, where she landed the part-time instructor job with Apple.

Former Apple marketing chief of Australasia, Ben Bowley, will fill Ryall's position at the end of the month.