Cookies enriched with sweet lupin flour were tested for their acceptability and tolerance in young adults, and compared with control cookies. A number of hematological, hepatic and renal tests were performed, as well as the measurement of allergic response, in order to detect possible changes induced by lupin. The study included 31 young adults assigned to two groups which comprised males and females, with mean ages of 26 +/- 6.5, and 27 +/- 5.9 years, respectively. The protein and energy intakes of the subjects were calculated, prior to the study, using the methods of dietary history and the 24-hr recall method. The subjects were free of any abnormalities detectable by medical history, physical examination, biochemical and hematological tests. Body weight and height were measured before the beginning of the study. The ratio weight/height of the individuals was calculated using the Jelliffe's standards. The mean values for the calorie and protein intakes were 1,919 kcal (SD +/- 655) and 59.3 g (SD +/- 22.7). The calorie contents of the control and experimental cookies were 507 and 610 kcal respectively, while the protein contents were 8.4 g and 24.1 g, respectively. The body weight of subjects in both groups increased significantly during the study (P less than 0.01 and P less than 0.02). No significant changes were recorded for other anthropometric parameters, except for the tricipital skinfold (P less than 0.01). Changes observed in hematological parameters were judged to be unrelated to lupin flour. The acceptability and tolerance to high levels of lupin flour were good. The above-mentioned results show that sweet lupin flour is a good and safe source of energy and protein for adults.