Objective: To identify evidence from comparative studies on the effects of psychiatric guideline implementation on provider performance and patient outcome. Effects of different implementation strategies were reviewed. Method: Articles published between 1966 and March 2006 were searched through electronic databases and hand search. A systematic review of comparative studies of structured implementation of specific psychiatric guidelines was performed. Rates of guideline adherence, provider performance data, illness detection and diagnostic accuracy rates were extracted in addition to patient relevant outcome data. Results: Eighteen studies (nine randomized-controlled trials, six non-randomized-controlled studies and three quasiexperimental before-and-after studies) were identified. Effects on provider performance or patient outcome were moderate and temporary in most cases. Studies with positive outcomes used complex multifaceted interventions or specific psychological methods to implement guidelines. Conclusion: There is insufficient high-quality evidence to draw firm conclusions on the effects of implementation of specific psychiatric guidelines.