Introduction: Azathioprine (AZA) is commonly used in myasthenia gravis (MG). Treatment may be prolonged, entailing significant risks and avoidable costs. Methods: We reviewed remission, relapse, and side-effect profiles in MG patients on AZA during treatment and after tapering off. We conducted an ambispective study and analyzed remission, relapse rates, and side-effect profiles in 117MG patients on AZA. Results: Thirty-nine patients (33.3%) achieved remission, and 36 (30.8%) achieved complete stable remission (CSR), with a 33% relapse rate. No AZA side effects were seen in 95 (81%) patients. Only duration of disease of >10 years (odds ratio 9.5, 95% confidence interval 2.4-36.9, P=0.001) was significantly associated with remission. Conclusions: AZA is well tolerated by MG patients, and about 30% go into CSR on long-term AZA. Muscle Nerve, 2016 Muscle Nerve54: 405-412, 2016