Cannabis is the most prevalent illicit drug used globally. Regulatory debate in Ireland on the decriminalisation of cannabis and legalisation for therapeutic purposes (CTP) is on-going. The study aimed to investigate Irish general practitioner (GP) attitudes toward decriminalisation of cannabis and assess levels of support for CTP. An online survey was administered to all GPs in the Irish College of General Practitioner (ICGP) database. A content analysis was conducted on open-ended survey questions, with five themes emerging. GPs were concerned around early onset of use and intergenerational impacts, vulnerabilities to drug induced psychosis, patient self-medication with cannabis and potential for misuse of prescribed cannabis. The study reflects concerns around the mental health consequences of cannabis use and potential for misuse in the event of legalisation, and the need for product regulation and an enhanced evidence base to support treatment decision making. Further research and medical education is warranted.