Beginning his defence at his trial in The Hague, he said he was a "tolerant man" who had sought peace in Bosnia.
Mr Karadzic was arrested in Belgrade in 2008 after almost 13 years on the run.
He faces 10 charges of genocide and crimes against humanity during the war in the 1990s, including the Srebrenica massacre and the siege of Sarajevo.
More than 7,000 Bosniak (Bosnian Muslim) men and boys were killed at Srebrenica in the worst single atrocity in Europe since the end of World War II.
During the 44-month siege of Sarajevo more than 12,000 civilians died.
Mr Karadzic, 67, went on trial at the International Criminal Tribunal for the former Yugoslavia (ICTY) in October 2009
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