Malnutrition in the elderly is often unrecognized and untreated. Reduced secretion of growth hormone (GH) has been suggested as a cause of decreased muscle and bone mass with aging. This pilot study characterized the nutritional response of elderly malnourished subjects to recombinant human GH (rhGH). Subjects were included if they were over 60 years of age, if weight was more than 20% below average body weight (ABW), and if serum albumin concentration was less than 3.8 g/dL. Subjects were divided into two groups: one received 100 micrograms/kg rhGH (Protropin, Genentech) intramuscularly (IM) daily for 21 days; the other received a daily control injection of normal saline (Controls -C) (0.1 mL/kg IM) for the same period of time. During the 3-week period, mid-arm muscle circumference (MAMC) increased an average of 0.6 cm in GH patients but fell in C subjects. There was a non-significant trend to a decreased caloric intake in the control group. Weight increased an average of 4.95 lbs (2.2 kg) in the GH treated group, and decreased an average of 4.9 lbs (2.2 kg) in C subjects (P less than 0.05). Urinary nitrogen retention occurred only in the growth hormone treated subjects (P less than 0.05). Somatomedin C (IGF-1) rose significantly in those treated with GH (P less than 0.05), while there was no change in the control group. There was a significant association between weight change and IGF 1 concentration (r = 0.837, P less than 0.05). Neither clinical edema nor hyperglycemia was noted. These findings suggest that GH may be an effective way of maintaining and enhancing weight in malnourished older individuals.