This paper reports the development of a simulation model of the radiotherapy department of Walsgrave Hospital and shows the results of experiments conducted using the model. In the radiotherapy department a key target is the number of days from the time that the consultant refers the patient to the department to the date that the patient receives their first treatment. Many factors can affect this time and this project has attempted to identify and quantify the effects of these factors. Initial discussions were held to provide a framework for the study. These discussions were followed by a series of visits to the department to observe the way in which it operates and to interview staff in each of the main areas of work. Following this a flow diagram of the department was produced. This was used as a basis for the development of a computer simulation model which represents the way in which a patient moves through the department, from referral by a consultant, to the planning of the treatment, to the treatment itself, and finally discharge from the hospital. A series of experiments was used to evaluate the effects of changes to the input to the model, the number of resources in the model and the way in which the department operates. Finally, recommendations are made for future work to develop the model further and suggestions are made for its application.