Objective: To identify the factors that predict the remission and relapses in myasthenia gravis (MG) patients improved by prednisone and tacrolimus treatment. Methods: A retrospective, observational cohort analysis of MG patients who achieved remission after receiving prednisone and tacrolimus were performed at Tongji Hospital. The main outcome measures were the time to remission, prednisone discontinuation, tacrolimus reduction-associated relapse, and treatment outcome. Results: After adding tacrolimus, 256 patients were able to achieve remission with a mean time to remission of 2.1 +/- 1.4 months. After a median follow-up of 2.9years, 167 patients (65.2%) discontinued prednisone, and 20 patients (7.8%) achieved complete stable remission. Moreover, 53 of the 109 patients who were tapering tacrolimus experienced relapses. In multivariable analysis, female sex, low tacrolimus concentrations, and quantitative myasthenia gravis (QMG) scores have a positive correlation with the time to remission; concomitant additional autoimmune disease (AID) and high anti-acetylcholine receptor antibody (AChR-ab) levels were significantly associated with low probabilities of prednisone discontinuation [odds ratio (OR)=0.312-0.912, respectively]; rapid tacrolimus decrement speed (>= 0.76 mg/year) was an independent predictor for the development of relapse during tapering tacrolimus (OR = 5.662). Conclusion: Sex, tacrolimus concentrations, and QMG scores can be used as potential predictors of the time to remission in MG patients treated with tacrolimus and prednisone. Prednisone should be tapered slowly, especially in patients with additional AID or high serum titers of AChR-ab. To avoid symptoms recurrence, the dose of tacrolimus should reduce slowly, not exceeding 0.76 mg/year.