OBJECTIVE: The study examined the impact of easy access to ambulatory services for patients with bipolar disorder in a clinic-based program at a Veterans Affairs medical center. Core program components included medication administration based on treatment algorithms, standardized psychoeducation, and easy access to a single primary nurse provider to enhance continuity of care. The program had no community outreach or extensive rehabilitation components. METHODS: The study used a mirror- image design to compare patients' data from the year before program entry when patients received standard clinical care with data for the first year in the program. Process and outcome data from the first 103 patients to complete one year are reported. RESULTS: The findings indicated increased patient satisfaction and increased intensity of medication treatment without increased side effects at one year. Although scheduled ambulatory clinic visits increased as expected, use of the emergency room and the psychiatric triage team decreased significantly. Patients who were high utilizers of care before program entry experienced significant reductions in psychiatric hospital days and total mental health expenditures. CONCLUSIONS: Easy access to ambulatory care, even if limited to clinic-based services, may have beneficial effects on important process and outcome measures for bipolar disorder. These effects may be attributable to on-demand access to services, continuity of care with a single primary provider, or improved medication delivery to reduce the "efficacy-effectiveness gap" for patients with bipolar disorder. Results indicate that augmenting, rather than limiting, access to ambulatory care for patients with major mental illnesses such as bipolar disorder may reduce overall mental health expenditures.