Rep. Henry Waxman, D-Los Angeles, was hospitalized at Cedars-Sinai Medical Center for what an aide called routine testing.
Waxman, 69, felt ill Tuesday and was taken to the hospital Tuesday, but spokeswoman Karen Lightfoot said he felt much better later.
It was unclear what the problem was.
Waxman, who has been in Congress since 1975, heads the House Energy and Commerce Committee.
Waxman's hospitalization came on the same day the Los Angeles Times gave a glowing review of "The Waxman Report: How Congress Really Works," a new book by Waxman and co-author Joshua Green. The review said the book is "part fascinating, shrewd civics lesson and part bracing statement of practical idealism" that is "impossible to put down and a joy to read ..."
The review, by the Times' Tim Rutten, said the three California politicians who may have had "the biggest impact on the largest number of American lives" were Chief Justice Earl Warren and President Ronald Reagan, both former governors, and Waxman. Waxman was included because, "Tens of millions of Americans are healthier, breathe cleaner air and live safer lives because of his legislative efforts."
Rutten said Waxman's legislative achievements "can be compared only to Sen. Ted Kennedy's."
