In order to identify clues to forensic pathologist's classification of suicide, the forensic files of 100 consecutive cases of suicide, and 22 cases of undetermined manner of death, were analysed. Some specific causes of death, suicidal communication and other circumstantial evidence suggesting suicidal intent explained all but three classifications. Problematic cases concerned death by poisoning and by submersion, alcohol-dependent persons and subjects with positive blood alcohol concentration at autopsy. Guidelines to support the police investigation as well as the medico-legal examination can probably reduce the number of undetermined cases in cases of possible suicide.