To investigate the features of recent unnatural deaths from mishaps and possible negligence related to medical practice, forensic autopsy cases (n=856) during the past 6 years (1996-2001) at our institute were reviewed. Among them, there were 28 cases of medical practice-related fatalities (male/female, n=16/12; range 32-87 years of age). Half of the cases (n=14) were related to possible negligence in nursing and care. These unnatural deaths were reported to the police by physicians in charge (n=14), second physicians and ambulance attendants (n=6), patients' relatives (n=6) and others (n=2). In most cases, there was an event, which was sudden, unexpected and clearly noticeable not only by the medical personnel but also by bystanders. The cases where the deaths were reported to the police by patients' relatives included unexpected deaths during medical treatments following accidental traumas (n=2) and an anesthetic accident. Clinically unexpected deaths should be more critically assessed by the physicians themselves on the basis of the rights, benefit and welfare of the patients.