Saddam sat quietly as the chief judge called a prosecution witness to take the stand. His six co-defendants all former members of his regime were present.
The deposed president and most of the other defendants were represented by court-appointed lawyers as defense counsel have been boycotting the trial for two months in protest against the court's refusal to give them more preparation time and other rulings.
Saddam and his co-defendants have pleaded innocent to charges of war crimes and crimes against humanity for their role in the military offensive against the Kurds, known as Operation Anfal, reports AP.
The prosecution says that about 180,000 people, mostly civilians, were killed in the 1987-88 crackdown. Saddam and one other defendant have also pleaded innocent to genocide.
If convicted, Saddam and his co-defendants could be condemned to death.