Muhammad Ali has been hospitalized in Phoenix, where he lives, and is being treated for a respiratory issue, family spokesman Bob Gunnell said in a statement on Thursday.
"He is being treated by his team of doctors and is in fair condition," Gunnell said. "A brief hospital stay is expected. At this time, the Muhammad Ali family respectfully requests privacy."
The legendary three-time heavyweight champion, who is 74, suffers from Parkinson's disease.
Ali, who retired from the ring in 1981, has been hospitalized a few times in recent years, including twice between late 2014 and early 2015, with a severe urinary tract infection initially diagnosed as pneumonia.