In the past decade, the therapeutic choices for patients with myasthenia gravis (MG) have not changed, except for the introduction of rituximab. There have been three placebo-controlled randomized trials in the past fifteen years, namely, those on azathioprine (AZP), mycophenolate mofetil (MMF) and tacrolimus. The trial for AZP was carried out on a relatively small number of patients (AZP, 15; placebo, 19), and its outcome showed the therapeutic effectiveness of AZP. The MMF trial was carried out on a large number of patients (MMF, 88; placebo, 88). The result showed no effect on primary and secondary endpoints. The tacrolimus trial was carried out in Japan on a relatively large number of patients (tacrolimus, 40; placebo, 40). Although the study could not reveal an effect on the primary endpoint, several secondary endpoints turned out to be affected. In all three studies, the therapeutic drugs were used in combination with steroid, and the safety and tolerability of the drugs were shown. In diseases with a relatively small affected population, such as MG, successful execution of well-designed clinical trials is difficult. We have to learn how to collect pieces of valuable information wisely from previous studies. The utilization of clinical literacy will be important in this medical practice.