The efficacy of total parenteral nutrition (TPN) in the protection of body composition, when given as an adjuvant to CVB (cisplatin-vinblastine-bleomycin) treatment to patients with testicular teratocarcinoma, was investigated. Twenty-three patients without previous malnutrition were randomized to receive either TPN or spontaneous oral intake only during their hospital stay, in the course of a total treatment period of 10 weeks. The patients spent weeks 1, 4, 7, and 10 in the hospital to undergo chemotherapy. Energy and nitrogen intakes were profoundly decreased in the spontaneous oral-intake group, whereas the intakes decreased in the TPN group only at home when they relied on oral intake. In spite of the cytotoxic drugs, the TPN group remained in nitrogen balance when undergoing TPN at the hospital. However, they lost substantial body weight and body nitrogen over 10 weeks when compared with the oral-intake group. This loss in body mass was mainly a result of the prolonged anorexia that all the patients had after weekly termination of chemotherapy. This study demonstrates that well-nourished patients can use intravenous nutrition even while receiving cytocidal and cytostatic drug administration. However, intermittent periods of adequate nutrition in the hospital had only a marginal impact, since the positive effects of nutrition were offset by the pronounced anorexia that occurred in all patients outside the hospital for a considerable time after cytostatic treatment.