"We look forward to Steve returning to Apple at the end of June," Apple spokesman Steve Dowling said, repeating a statement the company has used before.
Jobs, described as "a strict vegetarian, very much into Eastern mysticism," is said by two sources to have turned to alternative medicine to treat his health problems. "He believes anything can be treated naturally," one of the sources said, asking not to be named.
Jobs has been private about medical matters, including a case of pancreatic cancer that was successfully treated with surgery in 2004. Members of Apple's board of directors, sources said, persuaded him that his health was "a fiduciary issue," interwoven with the health of the company.
He was listed last year as 189th on the Forbes list of the world's billionaires, with a net worth of about $5.7 billion. After selling Pixar animation studios to The Walt Disney Company in 2006, he became a Disney board member and the company's largest shareholder. Disney is the parent company of ABCNews.com.
Analysts said Apple has done fine in Jobs' absence, partly because he has been available for big decisions, and partly because he has delegated day-to-day decisions for about five years.
Apple Inc., stock, which dropped to $78.20 a share in January after he announced he was going on leave, has since climbed to above $140 a share. It was down less than one percent today.
ABC's Laura Marquez and Steven Cheng contributed reporting for this story from San Francisco.