Three psychiatric conceptual models: addictive, obsessive-compulsive spectrum and mood spectrum disorder have been proposed for pathological gambling. The objectives of this paper are to (1) evaluate the evidence base from the most recent reviews of each model, (2) update the evidence through 2007 and (3) summarize the status of the evidence for the three models. Structured literature review and evidence grading. The evidence base supporting all three models is limited. The majority of the evidence is controlled, but not randomized studies that provide evidence of association. The addiction model satisfies several of the criteria formulated for the evaluation of associational evidence, but no model coherently explains all of the associational evidence. Heterogeneity among pathological gamblers or confounding could be the factors contributing to failures of the current conceptual models. New models such as multi-component or subtype models may be needed.