This study examined the nature and extent of methadone- and buprenorphine-related morbidity through a retrospective analysis of ambulance service records (N = 243) in Melbourne, Australia. Cases in which methadone and buprenorphine were implicated are examined. Demographic and presenting characteristics, transport outcomes, and other substance use were explored. There were 84 buprenorphine-related attendances and 159 methadone-related attendances recorded on the database over the 4-year period. Presenting signs (respiratory rate and Glasgow Coma Scale score) were lower in the methadone-related attendances. Most of the attendances resulted in transport to hospital. Most presentations did not involve traditional signs of opioid overdose, a finding that warrants further investigation. This is the first article to describe characteristics of methadone- and buprenorphine-related ambulance attendances, with results suggesting this may be a useful way to monitor harms associated with these medications in the future.