A court reunion of the two alleged chief architects of Serb atrocities during Bosnia's 1992-95 war lasted only around an hour as Mr Mladic repeatedly told judges he would not answer former Bosnian Serb president Mr Karadzic's questions, citing ill health and an unwillingness to risk incriminating himself.
The brief hearing marked the first time the two men had been seen together publicly since the aftermath of the war, but Mr Mladic's refusal to answer any questions beyond sketching a brief history of his military service meant it cast no new light on the conflict that left 100,000 people dead.
Mr Mladic was to have been one of Mr Karadzic's last defence witnesses. Mr Karadzic's lawyer Peter Robinson said the former Bosnian Serb leader plans to testify in his own defence next month.
Both Mr Karadzic and Mr Mladic disappeared after the guns fell silent in Bosnia as they attempted to evade capture and extradition to face trial in The Hague.
Mr Karadzic was finally captured in Serbia in 2008 and Mr Mladic was detained nearly three years later.