A clinical study of a new semisynthetic podophyllotoxin etoposide (NK 171) was performed by administering the drug to four patients with testicular tumors. The drug was given intravenously at a dose of 80-120 mg/m2/day for five days or orally at a dose of 200 mg/body/day for five days. Among the four patients, 1 CR, 1 NC and 2 PD were observed. One patient with a testicular tumor who was given oral etoposide achieved complete remission for 23 months. Patients experienced the following side effects: alopecia (75%); anorexia (50%): stomatitis, phlebitis, anemia and liver dysfunction (25%). None of these side effects, however, was serious or permanent. Currently, we are testing etoposide in combination chemotherapy.