In this paper we examine the prescribing process in a hospital to see whether information systems failure contributes to the occurrence of prescribing errors. Reason?s model of organisational failure [1] suggests that this may be the case. Reason (1990) identifies circumstances in work systems and processes where errors may occur. While Reason?s model has been applied in a medical context, it has not been previously linked to errors which result from Information Systems failure. It is held, however, that the model can be used as a predictive tool suggesting that prescribing errors have an increased likelihood of occurring if one or more of the types of failure identified in Reason?s model are present in the existing Information delivery process in a hospital. In this research we examine the application of Reason?s model in predicting prescribing errors and then calculate the extent to which these errors are evident in the hospital ward under examination.