Objective: This study discusses the potential and the limitations of medical workforce planning in outpatient psychiatry in Switzerland. Methods: Hypotheses concerning selected factors influencing the number of office-based psychiatrists needed in the future were formulated. In a next step, those hypotheses were assigned to one of three scenarios (high, constant, and normal need development). On the basis of these three scenarios, the number of psychiatrists needed was calculated. Results: Taken together, the results from the scenarios indicate an undersupply of office-based psychiatrists for the next 20 years. Conclusion: Estimating the number office-based psychiatrists needed in the future is basically feasible and reasonable. But according to the actual state of knowledge, only crude estimations are possible. There is a need for more research in this area.