In a randomized trial of 119 patients with small cell cancer of the lung, the effects of a 30-day course of central intravenous hyperalimentation (IVH) on dietary intake were evaluated. All patients underwent the same aggressive chemotherapy and radiation therapy; 57 patients received IVH and 62 served as controls. Median caloric intake prior to antineoplastic therapy was less than 1.2 times basal energy expenditure, below the maximum necessary to maintain weight. While receiving IVH, patients had increased caloric and protein intake. Once the IVH was stopped, oral intake was transiently depressed and thereafter similar to control patients. Baseline nutritional parameters, age, sex, and immediate toxicity from chemotherapy did not predict subsequent caloric insufficiency. Direct estimation of dietary intake is likely the most valuable measure in selecting patients who will need adjunctive nutritional support.