Over the past several years, tacrolimus has attracted attention as a new 
therapeutic drug for myasthenia gravis (MG), but few reports have considered its 
use for MG in pediatric patients, and most of these have focused on severe 
systemic MG. In this case report, we used tacrolimus to successfully treat a 
13-year-old boy with ocular MG who had suffered from severe steroid 
complications, including a failure of thrive and osteoporosis. He first showed 
symptoms of ocular MG at age 2 years 3 months. At age 13 years, he was receiving 
PSL (3.75 mg/day), but the symptoms of ocular MG recurred. We increased the 
dosage of oral PSL up to 30 mg/day, and three courses of mPSL pulse therapy were 
applied, but these therapies had only limited effect, and his symptoms worsened. 
Tacrolimus was started at 0.4 mg/day (0.011 mg/kg/day), and every 2 weeks the 
dose was gradually increased by 0.2 mg/day. His symptoms of MG began to improve 
3 weeks after the initial administration of tacrolimus. Approximately 3 months 
after the start of tacrolimus administration, PSL was discontinued. Currently, 
at 1 year and 4 months after the start of tacrolimus administration, while 
slight ptosis is observed in the evening, it does not influence his daily life, 
and his condition remains comparable to that when he stopped taking PSL. No 
adverse effects of tacrolimus have been recognized. In pediatric patients with 
steroid-dependent ocular MG without thymectomy, tacrolimus may be a safe and 
effective alternative to steroid and thymectomy.