Jewish Care fundraising director Richard Franklin is leaving to take up "a once in a lifetime opportunity to help fund solutions to some of the greatest health challenges of our time".
Mr Franklin, 45, is to join King's Health Partners as fundraising director of its "World Questions, King's Answers" campaign, led by Sir John Major, which has a £500 million target by 2015.
Wishing Mr Franklin well, Jewish Care chairman Stephen Zimmerman thanked him for "an outstanding job over the last eight years".
Mr Franklin had fundraised for medical ventures before joining Jewish Care and had also been a partner in a City law firm. At the charity, he oversaw significant growth in fundraising, most recently for projects including its £44 million care campus in Golders Green.
"Only now is the community starting to truly appreciate the extent to which Jewish Care requires their support in order to provide the kind of health and social care we would want for ourselves and our families," he said."British Jewry's ageing population needs the right services to be available in the right place.
"It will remain a significant challenge for the cha-rity to continue to meet their increasing needs."