Wearing a pinstriped gray suit instead of a pinstriped New York Yankees uniform, the seven-time Cy Young Award winner was accompanied by two attorneys.
Clemens declined to take questions from reporters on his way in, saying only, "Good morning," before heading into the offices of the House Oversight and Government Reform Committee.
The 45-year-old pitcher ranks eighth in major league history with 354 career wins. He put off retirement yet again in 2007, returning to the Yankees in June and going 6-6 with a 4.18 ERA.
His appearance on Capitol Hill came one day after his Yankees teammate and workout partner, Andy Pettitte, gave a deposition to committee staff for 2½ hours.
Both players' private interviews are part of preparation for a Feb. 13 hearing, a public session expected to focus on allegations made in the Mitchell Report by trainer Brian McNamee that he injected Clemens more than a dozen times with human growth hormone and steroids. Clemens has chosen various ways to strongly deny that, including a taped TV interview, a live news conference and, repeatedly, through his lawyers.
Tuesday's deposition was Clemens' first opportunity to address the allegations under oath. McNamee is to be interviewed by committee lawyers Thursday.
"You can be sure that Clemens' inquisitors will have figured out a dozen different ways, word for word,against him," says CBS News chief legal analyst Andrew Cohen. "All of these questions will be designed either to get Clemens caught in a perjury trap or to commit to a particular story about his relationship with his former personal trainer, Brian McNamee (in which case he'll be forever stuck with that story no matter what subsequent evidence shows)."
A former Yankees teammate of Pettitte and Clemens, Chuck Knoblauch, spoke to committee staff Friday. The day before, an employee of the sports agency that represents Clemens and Pettitte went to Capitol Hill to be interviewed. Another witness, former New York Mets clubhouse employee Kirk Radomski, is to speak to committee lawyers Feb. 12.
Former Senate Majority Leader George Mitchell's report on drugs in baseball, released in December, contains McNamee's accusations - first told to federal prosecutors, then repeated to Mitchell - that he injected Clemens with HGH and steroids in 1998, 2000 and 2001.
Clemens acknowledged he received injections from McNamee, but he said they were for vitamin B-12 and the painkiller lidocaine. His repeated denials about performance enhancers drew Congress' attention.
When Mitchell testified at a committee hearing Jan. 15, he was asked whether he was still comfortable with McNamee's credibility.
"We believe that the statements provided to us were truthful," Mitchell said.
One of McNamee's lawyers, Earl Ward, said Monday no decision had been made on whether he would submit to a deposition or transcribed interview Thursday. It is a crime to lie to Congress, whether sworn to tell the truth or not, so the distinction between the two has more to do with the format of the questioning and the confidentiality of the transcript.
McNamee also told Mitchell he injected Pettitte with HGH. Pettitte lent credence to Mitchell's findings by acknowledging two days after the report was released that he did try HGH for two days in 2002 to help deal with an elbow injury.
Pettitte did not take questions from the media after being deposed Monday. Indeed, he said only one word: "No," in response to whether he would talk to reporters.
"At the committee's request, Andy Pettitte voluntarily met with representatives of the committee this morning, and fully answered all of the inquiries made of him in a sworn deposition," two of Pettitte's lawyers, Jay Reisinger and Thomas Farrell, said in a statement.
"Out of respect for the sensitive nature of these proceedings, and out of deference to the committee's request for confidentiality, we, on behalf of Mr. Pettitte, will not comment on the nature or specifics of his testimony."
The committee announced Monday it will hold yet another hearing Feb. 12, titled "Myths and Facts about Human Growth Hormone, B-12, and Other Substances." The committee said medical experts will testify about the effects of such substances.