Ilgauskas will miss at least the first eight weeks of the season, the Cavs said Friday.
The decision was made after consulting with doctors at the Cleveland Clinic and Dr. Thomas Clanton in Houston.
"We are not going to speculate beyond that at this time," said vice president and general manager Jim Paxson.
"Our concern is the long-term health of a very good player. We will not rush into anything that is only a short-term approach," Paxson said.
The 7-foot-3 Ilgauskas missed the all but five games last season with a broken bone in the same foot.
He had a toe infection earlier this month that required treatment with antibiotics, and didn't play in any exhibition games.
The Cavs signed Ilgauskas to a six-year, $71 million contract extension just before last season.
Ilgauskas has a long history of foot problems. He broke his right foot in 1995 and 1996, keeping him out both years.
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