Binding sites for human growth hormone (hGH) were studied in liver membranes of rats with chronic renal insufficiency (CRI) associated with a marked growth defect. A subtotal nephrectomy was performed in young female rats. One month after surgery, the rats with a plasma creatinine greater than or equal to 3 times that of controls were killed. The specific binding of 125I-hGH to microsomal membranes of rats with CRI was low. The number of binding sites rather than the binding affinity was affected; the number of both lactogenic and somatotropic sites was decreased. The sites of the plasma membranes as well as intracellular sites of Golgi fractions were reduced. No modification of the plasma GH and PRL was found. The hormone level did not appear to be the main regulating factor of the GH binding sites in this system.