Objective: Despite substantial investment in Electronic Medical Record (EMR) systems there has been little research to evaluate them. Our aim was to evaluate changes in efficiency and quality of services after the introduction of a purpose built EMR system, and to assess its acceptability by the doctors, nurses and patients using it. Methods: We compared a nine month period before and after the introduction of an EMR system in a large sexual health service, audited a sample of records in both periods and undertook anonymous surveys of both staff and patients. Results: There were 9,752 doctor consultations (in 5,512 consulting hours) in the Paper Medical Record (PMR) period and 9,145 doctor consultations (in 5,176 consulting hours in the EMR period eligible for inclusion in the analysis. There were 5% more consultations per hour seen by doctors in the EMR period compared to the PMR period (rate ratio = 1.05; 95% confidence interval, 1.02, 1.08) after adjusting for type of consultation. The qualitative evaluation of 300 records for each period showed no difference in quality (P>0.17). A survey of clinicians demonstrated that doctors and nurses preferred the EMR system (P<0.01) and a patient survey in each period showed no difference in satisfaction of their care (97% for PMR, 95% for EMR, P = 0.61). Conclusion: The introduction of an integrated EMR improved efficiency while maintaining the quality of the patient record. The EMR was popular with staff and was not associated with a decline in patient satisfaction in the clinical care provided.