The notion of comorbidities within problem gambling populations has important clinical implications, particularly for appropriate treatment matching. The comorbidities most commonly cited in problem gambling literature include depression, anxiety, alcohol abuse and impulsivity. Previous research shows evidence of patterns in multiple co-occurring comorbidities and that there may be different subtypes of gamblers based on these patterns. To further the current understanding of gambling subtypes, the aim of our study was to identify subtypes of gamblers currently in treatment. Hierarchical Cluster Analysis yielded four mutually exclusive groups of 202 gamblers: (1) gamblers with comorbid psychological problems (35%); (2) 'pure' gamblers without other comorbidities (27%); (3) gamblers with comorbid alcohol abuse (25%); and (4) 'multimorbid' gamblers (13%). The four groups differed on demographic information, drug use and gambling behaviours including gambling activity and problem gambling severity. Gamblers with comorbid psychological problems were more likely to be older women on low income, more likely to report a family history of psychological problems and were more often electronic gaming machine players. As expected, 'pure' gamblers had lower problem gambling severity and were more likely to report current abstinence. Gamblers with comorbid alcohol abuse were more likely to be young men who used stimulant drugs, endorsed a higher quality of life and worked full-time. 'Multimorbid' gamblers were elevated on all comorbidities, had general problems related to their health and wellbeing and reported high rates of hostility and aggression. These groups combine elements of existing conceptual models of gambling subtypes and may require different treatments.