He said prosecutors had greatly exaggerated the frequency of his “licentious evenings”. There had only been 12 in three years, he said.
Strauss-Kahn is accused of helping to procure sex workers for a prostitution ring based at a hotel in Lille.
He has argued that he did not know the women were prostitutes.
Although using prostitutes is not illegal in France, supplying them or assisting their supply is an offence.
Prosecutors have been quoted as saying Mr Strauss-Khan, 65, played a pivotal role in facilitating the orgies, describing him as “party king”.
If found guilty, the one-time potential socialist candidate for the French presidency could face up to ten years in jail and a €1.5 (£1.1m) million fine.
Taking the stand yesterday, Strauss-Kahn told the court: “I committed no crime, no offence.
“The prosecution gives the impression of unbridled activity.”
But, he added, “there were only 12 parties in total – that is four a year over three years”.
As he arrived in court in Lille earlier, three topless protesters from the Femen activist group – with “pimps, clients, guilty” painted on their torsos – jumped on his car. They were taken away by police.
The former IMF chief, widely known by his initials DSK – is expected to give evidence for three days, and has not attended the trial since it opened on 2 February, when his appearance attracted widespread international media attention.
The day before he was due to testify, a former prostitute named Mounia described how she had been paid €900 by a businessman, David Roquet, for what she had been told would be a “small party”.
She told the court that she had been specifically chosen for Strauss-Khan and no-one else.
Mounia’s evidence is expected to play an important part in the trial, as the prosecution tries to prove that he knew she and another woman, Jade, were prostitutes.
Mr Roquet, 46, who was one of the men who organised the parties, said on Monday that he had taken part for “professional” purposes.
Participation was important for his construction business and it enabled him to have contact with Strauss-Kahn, he told the court.
“He did it for fun. We had some lovely evenings,” he said, adding that five or six couples would be involved at each party. Among the 13 co-accused are luxury hotel managers, a lawyer, a former police commissioner and a brothel owner nicknamed “Dodo the Pimp”.
They face charges of “aggravated pimping” while the former head of the IMF is accused of using business contacts to hire women for sexual parties in Paris, Lille and Washington DC.
Strauss-Kahn stepped down from the IMF after being accused of attempted rape by a hotel maid in New York in 2011.
The trial continues.