We reviewed 32 cases where a forensic autopsy detected methamphetamine in the blood, and all of these autopsies were performed at two institutes between 1991 and 2003. In accordance with several criteria, the blood concentration in 11 cases was classified as above the toxic level, and 10 of these cases were diagnosed as methamphetamine poisoning. In 20 cases (62.5% of total cases), the blood concentration was of a 'toxic level', and 10, 2 and 1 of these cases were diagnosed as methamphetamine poisoning, cardiomyopathy and intracerebral hemorrhage, respectively. Since it is unclear how the effects of methamphetamine may contribute to the death of an individual, a diagnosis of the exact cause of death is often difficult to make in cases where the blood concentration of methamphetamine was of a 'toxic level'. Therefore, a diagnosis has to be carefully made in consideration of the pathological findings, the pharmacological effects of methamphetamine and the process until death in such cases. Additionally, the mechanism of methamphetamine-related death needs to be more fully studied to enable an appropriate diagnosis to be made easily.