Résumé : Background & Aims: There are few well-designed studies evaluating the effect of oral nutrition supplements in patients with cancer cachexia. The aim of this study, in a posthoc analysis, was to examine the effect of dietary compliance on intake and body composition in patients with unresectable pancreatic cancer. Methods: Two hundred patients were randomised to receive 2 cans/day of a protein and energy dense, oral nutrition supplement ±n-3 fatty acids in an international, multi-centre randomised trial over 8 weeks. Dietary compliance was defined a priori as consumption of a minimum of 1.5 cans/day of either supplement. Body composition, dietary intake and quality of life were measured at baseline, 4 and 8 weeks. Results: On average, there were significant differences in energy intake (501 kcal), protein intake (25.4 g) and weight (1.7 kg) between patients who were compliant with the nutrition prescription compared to noncompliant patients controlling for n-3 fatty acid randomisation, baseline weight and quality of life. Over the 8-week period, there was significant improvement in weight only. There was no significant difference in the energy intake from meals of the total group over the 8 weeks. Conclusions: Compliance with the prescription of 1.5 cans of a protein and energy dense, oral nutrition supplement ±n-3 fatty acids improved nutrition related outcomes in untreated pancreatic cancer patients. This level of supplement intake does not inhibit meal intake. © 2005 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.