AbstractModelling the operation of outpatient departments, with the aim of devising an appointment system that would reduce patient waiting time, was an early application area for O.R. Yet outpatients still spend an excessive amount of time waiting. This paper reports an investigation into the operation of outpatient departments. The attempt to arrive at a sensible policy is considered at length. It is concluded that the determination of an implementable policy, the education of participants into acceptance of that policy, and monitoring any policy once implemented are of paramount importance. The approach taken is briefly compared with qualitative and soft approaches.