The present study was performed to clarify the possibility of IGF-I as an early indicator of malnutrition in patients with end-stage renal disease. Thirty-two patients (19 males, 13 females; mean age 49.6 ± 10.0 years) undergoing dialysis were enrolled in the study. Body weight, skinfold thickness, and midarm muscle circumferences (MAMCs) were measured for anthropometric nutritional indices. Blood samples were collected to measure the following endocrinological, biochemical and hematological indices: IGF-I, growth hormone, (GH), total protein, prealbumin, albumin, transferrin, hematocrit, and lymphocyte count. Nutritional indices were measured again 1 month later to calculate the percent difference among them. Moreover, 2 patients who showed a decrease in IGF-I and suffered from malnutritional complications, such as hypoproteinemia and emaciation, which could not be successfully treated by conventional therapies were selected in order to confirm the nutritional role of IGF-I mediated by recombinant human GH (r-hGH). The serum IGF-I concentration distribution ranged from 22 to 225 ng/ml. In 15 patients (10 males, 5 females), it fell from 22 to 82 ng/ml below the normal range. Partial correlation coefficient analysis demonstrated that baseline IGF-I and the percent difference of each the body weight, MAMC, prealbumin and albumin were highly significantly correlated (r = 0.431, 0.641, 0.624 and 0.348, respectively; p = 0.014, 0.001, 0.001 and 0.028, respectively). The percent difference of IGF-I did not correlate significantly with that of any other nutritional index during the 1-month observation without administration of r-hGH. However, the correction of serum IGF-I by the short-term administration of r-hGH obviously increased plasma protein and albumin, peripheral erythrocate and lymphocyte counts, and body weight. From these results, we conclude that IGF-I is a good indicator which may reflect the initiation of a malnutritional state in patients with chronic renal failure