We describe a case of non-classical congenital adrenal hyperplasia (NCCAH) due to 21-hydroxylase deficiency in a 30-year-old Japanese woman who achieved pregnancy after treatment of primary amenorrhea. Hirsutism and clitoromegaly were present. Ultrasound examination showed polycystic appearance of the ovary. Luteinizing hormone-releasing hormone (LH-RH) test resulted in exaggerated LH response, showing a polycystic ovary syndrome (PCOS) pattern. The diagnosis was based on the elevated intial levels of 17-hydroxyprogesterone (55 ng/mL) and dihydroepiandosterone (7780 ng/mL). The first withdrawal bleeding occurred within 6 weeks after treatment with hydrocortisone (20 mg/day) combined with conjugated estrogens (1.25 mg/day) and medroxyprogesterone acetate (10 mg/day), which were continued for five courses. The bleeding remained cyclic every 28 days with maintenance doses of hydrocortisone. Subsequently, ovulation was induced using clomiphene citrate (100 mg/day). Pregnancy was achieved at the second attempt of ovulation induction and was within 10 months after initial presentation. Continuing hydrocortisone, the patient delivered a healthy baby at term.