A systematic effort is underway to rationalize the planning of physician supply. This paper summarizes the current methodologies available and focuses on the attempts to determine the optimal psychiatrist-to-population ratio in Canada. The impact of several variables influencing this ratio is discussed. An outline of the correlation between target physician supply and requirements of future trainees is presented. While the relevant methodology is rapidly evolving, an improved process of data collection is urgently required. A number of challenges for our profession lay ahead, such as the need for sensitive and reliable measures of the adequacy of psychiatrist and subspecialist supply and public issues arising from the poor geographic distribution of psychiatric manpower.