Even though more than a decade has passed since the creation of the International Criminal Tribunal for the Former Yugoslavia, the law of the most fundamental concept in international criminal law – mens rea – remains unsettled. Through its jurisprudence, the Yugoslavia Tribunal has made enormous efforts to assign different degrees of mens rea for different categories of crimes under its Statute. The present study is an attempt to clarify several issues with regard to the law of mens rea as developed in the case law of the Yugoslavia Tribunal. Among these issues are the following: what precisely is to be understood by the terms "specific intent", "special intent", "dolus specialis", or "surplus intent"? Similarly, what are the precise meanings of the terms "deliberately", "intention", "intent", "intentionally", "wilful or wilfully", "knowledge", and "wanton" as provided for in the ICTY Statute or as employed by the Chambers within its judgments.