The verdict was the latest blow to the government's legal pursuit of athletes accused of illicit drug use.
A seven-year investigation into home run king Barry Bonds yielded a guilty verdict on only one count of obstruction of justice in a San Francisco court last year, with the jury deadlocked on whether Bonds lied to a grand jury when he denied knowingly taking performance-enhancing drugs.
A two-year, multicontinent investigation of cyclist Lance Armstrong was recently closed with no charges brought, though the U.S. Anti-Doping Agency filed formal accusations last week that could strip the seven-time Tour de France winner of his victories in that storied race. Armstrong denies any doping.
Late Monday, as the jury foreman read the acquittal on the final count, Clemens bit his lower lip and rubbed a tear from his eye.
Clemens, family members and his lawyers took turns exchanging hugs. At one point, Clemens and his four sons gathered in the middle of the courtroom, arms interlocked like football players in a huddle, and sobbing could be heard. Debbie Clemens dabbed her husband's eyes with a tissue.
Accused of cheating to achieve and extend his success and then facing felony charges that he lied about it Clemens declared outside the courthouse, "I put a lot of hard work into that career."
His chief lawyer, Rusty Hardin, walked up to a bank of microphones and exclaimed: "Wow!"
Hardin said Clemens had to hustle to get to court in time to hear the verdict. "All of us had told Roger there wouldn't be a verdict for two, three or four days, so he was actually working out with his sons almost at the Washington Monument when he got the call that there was a verdict."
Prosecutors declined to comment as they left the courthouse. But the U.S. Attorney's Office said in a written statement, "The jury has spoken in this matter, and we thank them for their service. We respect the judicial process and the jury's verdict."
Clemens, 49, was charged with two counts of perjury, three counts of making false statements and one count of obstructing Congress when he testified at a deposition and at a nationally televised hearing in February 2008. The charges centered on his repeated denials that he used steroids and human growth hormone during a 24-year career produced 354 victories.
The first attempt to try Clemens last year ended in a mistrial when prosecutors played a snippet of video evidence that had previously been ruled inadmissible.
Still, Monday's verdict is unlikely to settle the matter in sports circles as to whether Clemens cheated in the latter stages of a remarkable career that extended into a period in which performance-enhancing drug use in baseball was thought to be prevalent. Clemens himself told Congress at the 2008 hearing that "no matter what we discuss here today, I'm never going to have my name restored."
A crucial barometer comes this fall, when Clemens' name appears on the Hall of Fame ballot for the first time.