In anovulatory patients ovulation is usually induced by clomiphene citrate (CC) or gonadotropin therapy, but in the case of polycystic ovary syndrome (PCOS), diagnosed by the presence of several micropolycysts in the ovaries and a high LH/FSH ratio in the serum, CC is only minimally effective, and side effects are often a problem with gonadotropin therapy. In the present study we administered a Chinese herbal medicine Sairei-to which appears to have a steroidal effect in anovulatory PCOS patients. As a result of the treatment, serum LH and the LH/FSH ratio significantly decreased (P<0.01) and the ovulatory rate was 70.6%. Serum testosterone levels were within normal limits before the treatment, and did not significantly change during the treatment. Sairei-to may therefore be useful for the treatment of anovulation in PCOS patients.