A man in his late twenties collapsed shortly after intravenously injecting himself with methamphetamine (MA). He slipped into a deep coma and remained in this condition for 9 days, until his death. Autopsy revealed severe brain edema and localized subarachnoid hemorrhages in the cerebrum and cerebellum. Histopathological examination revealed myocardial necrosis in the left ventricle, rhabdomyolysis and bronchopneumonia. Blood derived from the cadaver was found to have high levels of blood urea nitrogen and creatinine, suggesting he experienced acute renal failure probably due to rhabdomyolysis. Most of the postmortem findings were consistent with MA poisoning. The patient's bronchopneumonia may have represented a hypostatic pneumonia that developed as a result of his deep coma. While the patient's brain edema, myocardial necrosis and rhabdomyolysis were diagnosed soon after admission, his bronchopneumonia and acute renal failure only occurred 6 and 8 days later, respectively. Although MA was not detected in the cadaver's blood, urine or liver, analysis of the decedent's hair using gas chromatography-mass spectrometry confirmed its presence at a concentration of 1.1 ng/mg. Based on these findings, we concluded that the patient's cause of death was multiorganopathy resulting from MA poisoning. This case suggests that the postmortem diagnosis of MA poisoning in patients who survive for relatively longer periods after drug injection should include toxicological hair analysis in combination with histopathological and postmortem physiochemical examination.