ObjectiveTo analyze the characteristics of methadone-related poisoning cases and provide a reference for forensic identification.MethodsA total of 71 cases of methadone-related poisoning reported from 1998 to 2023 in China and 26 cases of methadone-related deaths reported from 2013 to 2018 in Italy were retrieved from databases including PubMed, Wanfang and CNKI. The general information, forensic pathological and toxicological characteristics were analyzed.ResultsAmong the 71 methadone-related poisoning cases in China, there were 54 cases (76.06%) of poisoning without death and 17 cases (23.94%) of death from poisoning. There were 54 male cases (76.06%), and 51 cases (71.83%) aged 19 to 39 years old. There were 35 cases (49.30%) of poisoning caused by methadone alone, and 32 cases (45.07%) were poisoning caused by methadone combined with other substances or drugs including heroin and benzodiazepines. Most of the poisoned showed coma, respiratory depression and miosis. Signs of asphyxia were often found by autopsy. The mass concentration of methadone detected in the blood of 6 deceased ranged from 0.112 to 3.000 mg/L. Among the 26 methadone-related deaths in Italy, 22 cases were male (84.62%). There were 6 cases (23.08%) caused by methadone alone, and 20 cases (76.92%) died from methadone combined with other substances or drugs. The mass concentration of methadone in blood ranged from 0.181 to 4.059 mg/L.ConclusionThe proportions of poisoning cases caused by methadone alone and methadone combined with other substances or drugs are comparable in China. The majority of deceased caused by methadone poisoning shows typical triad of coma, respiratory depression and miosis, which helps forensic experts determine the cause of death related to methadone. Additionally, it is necessary to increase the routine testing of the concentration of methadone and its combined substances or drugs in deceased, and collect data for the interpretation of the results of related cases.