Drowning is one of the leading causes of death when the manner of death remains undetermined. In the present study, we examined the epidemiological and medico-legal profile of 276 undetermined deaths (M:F=3.4:1; mean age 41.9+/-16.0 SD) among 1,707 consecutive bodies found in water and autopsied at the Department of Forensic Medicine, University of Helsinki, from 1976 to 2000. We also describe the differences between the police investigator's initial opinion and the forensic pathologist's death certification, and the different approaches among forensic pathologists when determining the cause of death. There was considerable variation among individual pathologists in the percentage of deaths considered undetermined but these differences were not significantly related to their level of training. Medico-legal training should focus on a standardised diagnostic approach to borderline cases, in which essential factors in determining the manner of death are often ambiguous.