Seven former Bosnian Serb officers are on trial for genocide in one of the most important cases in the history of the tribunal.
This comes four months after the death of Slobodan Milosevic, the former Yugoslav president, who died before the completion of his trial on charges of genocide.
The trial began in the week that marks the anniversary of the massacre of 8,000 Muslim men and boys by Bosnian Serb forces in 1995. The town in eastern Bosnia had been designated a "safe area" by the UN before the massacres.
Carla del Ponte, the tribunal chief prosecutor, was to give an opening statement on Friday before the court adjourns for its summer break.
The case is due to resume in late August.
Justice for all
The tribunal has been criticised for its failure to capture and put on trial the two men who are viewed as the chief architects of the slaughter - Radovan Karadzic, the former Bosnian Serb leader, and his military chief, General Ratko Mladic. Both men have been on the run for more than 10 years.
Meanwhile, relatives reburied the dead this week, after about 505 bodies were exhumed from mass graves to be formally identified. Thousands remain missing.
Del Ponte attended Tuesday's commemoration in Srebrenica, partly to focus attention on efforts to have the two chief suspects arrested.
Speaking at the ceremony, Del Ponte said: "I'm here for the ceremony, for the victims, for the survivors and for the criminals Karadzic and Mladic who are still at large."