Short-term lower leg length was measured longitudinally using a high-precision device called a knemometer in 11 children with chronic renal failure and 12 normal children. The method has a high accuracy (mean standard error 0.13 mm) and may prove useful for prediction of long-term total body growth. Its application in renal patients undergoing corticosteroid, growth hormone (GH) and erythropoietin (EPO) therapy is documented. GH was shown to improve lower leg growth in an adolescent who already had passed the maximum of his pubertal spurt. EPO treatment produced no consistent increase of short-term growth.