General practitioners' prescribing habits were studied using encounter forms during a period of three years. Analysis of the first year's forms revealed examples of inappropriate prescribing, so an audit was undertaken on the treatment of fungal skin infections and coughs and colds in children. Data collection was continued for a further year to measure any changes in prescribing. Analysis after audit showed that more appropriate prescribing had reduced the number of drugs prescribed as well as the number of repeat consultations needed before resolution of the problem. These findings suggest that the continuous use of encounter forms can accurately reveal the prescribing habits of general practitioners. Self-audit can then be performed on a continuing basis with little disruption of the general practitioner's normal routine.