Twenty-eight patients with "poor prognosis" metastatic gestational trophoblastic disease were treated during a 17-year period. The primary treatment was combination chemotherapy with methotrexate, actinomycin D, and chlorambucil (MAC). Patients who failed to respond to this regimen were treated secondarily with other combinations. Adjuvant surgery and radiotherapy were used in selected cases. The overall remission rate was 89% (25 of 28): 71% for first-line treatment with MAC (20 of 28) and 62% for second-line treatment (five of eight). The response rate to MAC correlated well with the patient's score (modified World Health Organization [WHO] scoring system--1983). Seventeen patients treated with MAC had scores less than 12, and all of them achieved remission. Of 11 patients having scores of 12 or more, only three achieved remission with MAC (27%). Of the eight who did not, five achieved remission with other combinations (62%) and three died. No patient died because of chemotherapy toxicity. The WHO scoring system is a good index to select high-risk patients who need primary chemotherapy more aggressive than MAC.