ABSTRACT Introduction: Although thymectomy is an important therapeutic option for myasthenia gravis (MG), factors predicting remission after thymectomy are not well known. Methods: We retrospectively reviewed patients with acetylcholine receptor antibody (AChR‐Ab)‐positive MG who had undergone thymectomy. Prognostic factors predicting remission were investigated. Changes in AChR‐Ab titer before and after thymectomy were also evaluated. Results: Among the 179 patients, 52.5% achieved complete stable or pharmacologic remission. Nonthymomatous pathology and mild preoperative status were favorable predictors of remission. The decrease in AChR‐Ab titer after thymectomy was significant in nonthymomatous MG but not in thymomatous MG. Discussion: Nonthymomatous pathology and mild preoperative status are prognostic factors that may predict remission after thymectomy. The decrease in AChR‐Ab titer after thymectomy was significant in nonthymomatous MG but not in thymomatous MG, suggesting that the pathogenic role of the thymus differs according to pathology. Muscle Nerve 58:796–800, 2018