RNA analysis offers insight into diseases and mechanisms leading to death and could develop into a valuable tool for diagnosis of the cause of death in forensic pathology. Other possible applications include the determination of the age of wounds and injuries and of the post-mortem interval. The molecular identification of body fluids by analysis of cell-specific mRNA expression already represents a new technique supplementing DNA analysis in forensic cases. This review explains and discusses principles, techniques and applications by offering a complete and comprehensive overview of research results in forensic RNA work.