By Ian Simpson

WASHINGTON (Reuters) - New York Yankees' pitcher Andy Pettitte testified on Tuesday that former teammate and close friend Roger Clemens admitted to taking human growth hormone during a conversation they had while working out together in 1999 or 2000.

Pettitte is one of the most anticipated witnesses in the trial of Clemens, charged with lying to Congress about his alleged use of performance-enhancing drugs. They became confidants as teammates and longtime friends who worked with the same personal trainer, Brian McNamee, another important figure in the case.

In testimony on Tuesday, Pettitte told jurors that Clemens had spoken to him about drug use.

"Clemens mentioned that he had taken human growth hormone, it could help with recovery and that's all I really remember about the conversation," he testified.

Under questioning by prosecutor Steven Durham, Pettitte said the conversation occurred during an off-season workout in 1999 or 2000 with McNamee at Clemens' home in Houston.

Pettitte, who gave brief answers, said he had not heard of human growth hormone prior to that conversation. He said he later brought the subject up with McNamee, possibly the same day.

Clemens, 49, a seven-time winner of the Cy Young award, baseball's highest annual honor for a pitcher, watched Pettitte without emotion, sitting forward in his seat at the defense table.

Pettitte has admitted using human growth hormones in 2002 and 2004. He also testified to a congressional committee that Clemens told him in 1999 or 2000 and then again in 2005 that he had used human growth hormone. Clemens told the panel that while Pettitte was a close friend, he "misremembers" the conversations.

As his testimony began, Pettitte, dressed in light gray suit, striped tie and white shirt, said he had considered Clemens a mentor and would go to him for advice.

"We hit it off immediately" after Clemens was traded to the Yankees from the Toronto Blue Jays in 1999, Pettitte, 39, told jurors. "We had the same agent so we had a connection there ... It was a good situation."

Asked if he had affection for Clemens, Pettitte said, "Yes," all along not looking at his former teammate.

Pettitte and Clemens, both high school stars in Texas, both stars with the Yankees and Houston Astros, worked out together during the off season and often acknowledged their close relationship.


Pettitte, the second witness in the case, was something of a surprise since prosecutors have not disclosed the order of appearance of their witnesses.

He told jurors that he regretted ever taking human growth hormone. "I wish I never would have," he said, because of the furor stirred up by reports he had used it and the impact of drug use on children.

"If I never would have done it, I wouldn't be here today," he said, adding he was uncertain that it had helped him recover from injuries - the reason he had used it.

Clemens is being tried for a second time on federal charges of lying to the House of Representatives Committee on Oversight and Government Reform in 2008 about whether he used anabolic steroids and human growth hormone. The panel was investigating drug use in Major League baseball.

The trial of Clemens is expected to last about six weeks.

Clemens first went on trial last July, but Judge Reggie Walton declared a mistrial because prosecutors showed jurors a video clip that included material he had banned from the case unless it was raised by Clemens' defense team.

Pettitte has come out of retirement to bolster the Yankees' pitching staff and is playing his way back into shape with a Yankee farm club.

Pettitte took the stand after Hardin, Clemens' attorney, finished questioning the first witness, former Oversight Committee chief of staff Phil Barnett.

Barnett said he had "serious doubts" about the accuracy of Clemens' deposition before the panel on his use of human growth hormone.

(Editing by Paul Thomasch and Philip Barbara)