The efficacy of adjuvant parenteral nutrition (PN) in cancer patients is not well defined. Twenty-one of 42 patients with advanced diffuse lymphoma were randomly selected to receive PN during an aggressive program of multiple-drug chemotherapy. These patients received 56 courses of central venous PN support during the first 14 days of the 28-day cycles of early and late phases of chemotherapy. PN patients received an average of 2,216 kcal/day, and their oral intake was 836 kcal/day during therapy. PN patients had marked weight gains, and standard nutrition (SN) patients had stable weights both during cycles of therapy and over the entire course of therapy. Lean body mass, as indicated by total body potassium, anthropomorphic measurements, serum albumin, creatinine-to-height ratio, total iron-binding capacity, and total lymphocyte count, was not improved in PN patients as compared to SN patients. PN therapy was complicated by symptomatic subclavian vein thromboses, septic catheters, and pneumothoraxes. The actuarial survival rate at 2 years was 68.8% +/- 10.9% (estimate +/- SD) for PN patients and 65.8% +/- 12.2% (estimate +/- SD) for SN patients. These results suggest that the weight gained by PN patients was composed of fat, water, or both. A lack of improvement in nutritional status and survival rates and a significant complication rate were associated with adjuvant PN during chemotherapy.