In industrial countries protein-calorie malnutrition (PCM) is a frequent cause of hospital morbidity and mortality. In this study, 88 hospital patients were evaluated: 44 (25 men and 19 women) aged from 20 to 80 years) with PCM, and 44 without malnutrition; the two groups were matched with regard to sex, age and height. The following parameters were determined: arm muscle surface, whole-body muscle mass, proportion of body fat, serum albumin (Alb), prealbumin (PA), retinol-binding protein (RBP), transferrin, thyroxine-binding protein, thyroxine, triiodothyronine, reverse triiodothyronine and total complement. Anthropometric measurements were validated by planimetry of a computerized tomographic section of the arm in 60 patients. There were significant differences between the two sexes in anthropometric values. Alb, PA and RBP values were different in men and RBP only in women; all other biochemical parameters were the same in both sexes. Thus, the group with PCM could be distinguished from the control group by anthropometric values and RBP values. Anthropometric parameters have been reported as being more specific of PCM than biochemical parameters, but since the latter are considered more sensitive, both complement each other and must be taken into account.