The present study examined the influence of a computerized medical record summary system on incidence and length of hospitalization. Additional indicators of process of care were also considered. A prospective, randomized design was used where 241 experimental patients had a computerized medical record summary and 238 control patients had the traditional medical record. All patients were followed and compared over a two-year period. Although no difference in incidence of hospitalization was found between patients with and without the summary, during the second year, patients with summaries spent fewer days in the hospital. Patients with summaries also had more completed referrals for consultation, assigned diets, detected new problems and diagnostic tests on record than patients without the summary.