This paper describes computer simulation models of the utilization of shared resources by two E.N.T. consultants and two ophthalmology consultants in an English hospital. The resources in question are the hospital beds used by their patients, which are in the same wards, and the operating theatre, whose use they share. The validity of the models in relation to the actual system studied is assessed and experiments are described which evaluate alternative arrangements for the use of these resources. The models are discussed both as part of a continuing programme of research into hospital decision-making and as tools aiding the evaluation of the options open to hospital staff faced with a specific problem.