President Clinton has told the American people that he had a relationship with Ms Monica Lewisnky that was "not appropriate" and "wrong". He said it was a "critical lapse of judgment" on his part and "a personal failure for which I am solely and completely responsible".
The President addressed the American people at 3 a.m. Irish time, 5 1/2 hours after he concluded testimony to a grand jury conducting a criminal investigation into his own conduct.
The admission was a dramatic reversal of seven months of denials by the President and his aides that he had sexual relations with Ms Lewinsky.
In his televised address, he said: "This afternoon in this room, from this chair, I testified before the office of the independent council and the grand jury.
"I answered their questions truthfully, including questions about my private life, questions which no American citizen would ever want to answer. Still, I must take complete responsibility for all my actions both public and private."
He continued: "As you know, in a deposition in January I was asked questions about my relationship with Monica Lewinsky. While my answers were legally accurate I did not volunteer information. Indeed, I did have a relationship with Ms Lewinsky which was not appropriate. In fact, it was wrong.
"It constituted a critical lapse in judgment and personal failure on my part, for which I am solely and completely responsible. But I told the grand jury today and I say to you now that at no time did I ask anyone to lie, to hide or destroy evidence, or to take any other unlawful action.
"I know that my public comments and my silence about this matter gave a false impression. I misled people including even my wife. I deeply regret that.
"I can only tell you that I was motivated by many factors. First, by a desire to protect myself from the embarrassment of my own conduct. I was also very concerned about protecting my family. The fact that these questions were being asked in a politically-inspired law suit, which has since been dismissed, was a consideration too."
"Now this matter is between me and the two people I love most, my wife and our daughter, and our God. I must put it right and I am prepared to do whatever it takes to do so. Nothing is more important to me personally, but it is private, and I intend to reclaim my family life for my family. "It is nobody's business but ours. Even presidents have private lives. It is time to stop the pursuit of personal destruction and the prying into private lives and get on with our national life."
The admission was a dramatic reversal of seven months of denials by the President and his aides that he had sexual relations with Ms Lewinsky. But Mr Clinton and his political supporters will hope that the humiliating admission will remove any threat of impeachment by Congress.
Soon after the President ended his testimony to the grand jury from the Map Room of the White House, aides began telephoning senior Democrats in a damage limitation exercise. Many Democrats are said to feel betrayed after defending him for months against allegations of an affair with Ms Lewinsky.