Clemens, whose career includes 354 victories and seven Cy Young Awards as his league's best pitcher, had vehemently denied the use of performance-enhancing substances since his name surfaced in a report about drug use in the Major Leagues.
He was accompanied by two attorneys Tuesday when he entered the closed session with lawyers for the House Oversight and Government Reform Committee. Former New York Yankees teammate Andy Pettitte appeared for about two hours Monday. Clemens' session lasted more than five hours.
"I just want to thank the committee, the staff that I just met with," Clemens said leaving the meeting room. "They were very courteous. It was great to be able to tell them what I've been saying all along -- that I never used steroids or (human) growth hormone. I look forward to being here, I guess, in this room next week."
Players and others named in the report -- including the trainer who alleged Clemens used human growth hormone at least 16 times from 1998-2001 -- are to appear in open congressional sessions a week from Wednesday.
Clemens said the only substances trainer Brian McNamee ever injected into him was a pain-killer called lidocaine and vitamin B-12.
The House committee called the session after a group led by former U.S. Sen. George Mitchell, D-Maine, issued a report that alleged some 90 current and former players had used performance-enhancing substances such as steroids.