To assess the usefulness of nutritional status at diagnosis, we studied a group of 87 adult patients with diffuse large cell lymphoma (DLCL) in a prospective clinical trial. Nutritional status (NS) was measured by the combination of triceps skinfold, arm circumference and serum determinations of albumin and transferrin. Normal values were considered if the nutritional index was < 40, malnutrition was considered when the nutritional index was > 40. Fifty one (58%) of the patients presented with malnutrition at diagnosis with a nutritional index > 40. Malnourished patients had a significantly poorer outcome than well-nourished patients because overall survival was better: 57+ months (mean) in well-nourished patients compared to only 14 months (mean) in malnourished patients. Disease-free survival was also better in the patients with normal NS: 48% compared to 10% in patients with abnormal NS. Chemotherapy was better tolerated in the well-nourished cases with less delay in treatment schedule, less episodes of severe myelosuppression and infection and more dose intensity than patients with nutritional index > 40. Multivariable analysis indicates that malnutrition was a poor prognostic factor independent of other prognostic factors. We believe that malnutrition itself might be included as an adverse prognostic factor in patients with DLCL and studies to improve this clinical situation will be conducted.