Twelve of the alleged victims have tested positive for HIV.
What drove the three to commit such a ghastly crime remains unclear. Whether they were motivated by sheer perversion or it was simply a case of uncontrollable gay passion remains to be seen.
The three defendants, all HIV-positive, deny the charges, though. They face up to 21 years in prison if convicted.
They are charged with assault, rape and possession of illegal drugs.
The court, in the northern city of Groningen, heard that the three men allegedly drugged their party guests with a combination of ecstasy and a date rape drug before sexually assaulting them and injecting them with their own HIV-positive blood.
A lawyer for the alleged victims said they would launch a civil case for compensation if the defendants were convicted.
"They are hoping the trial will provide an answer to the question of why this happened to them," said the lawyer, Fred Kappelhof.