The chemotherapeutic effects of cis-diamminedichloro-platinum+vinblastine+bleomycin (PVB) on 3 human yolk sac tumors (YST-1, YST-2, and YST-3) of the ovary, which were heterotransplanted into BALB/c nude mice, were compared with the effects of vincris-tine+actinomycin D+cyclophosphamide (VAG), the combination currently favored for treatment of yolk sac tumors, PVB and VAC therapies were performed for 3 weeks. Both PVB and V AC significantly reduced the tumor volume of all the treated tumors. The mean weights of tumors in animals treated with PVB or VAC were, in percent of the mean tumor weight in untreated animals: 1.3 and 1.6 for YST-1 , 2.5 and 3.3 for YST-2, and 5.5 and 2.7 for YST-3, respectively. A strong correlation was noted between tumor volume and alpha-fetoprotein level in the sera of mice bearing YST-1 or TST-2 tumors.-JNCI 1983; 71 :1221-1225.