The authors studied the hand bones in 83 uremic patients undergoing periodic hemodialytic treatment, with microfocus and magnification, valuing particularly the debated findings of cortical striation (tunnelling). In 33 cases the radiological signs have been compared with the values of plasma parathyroid hormone and a significant relationship was found between the hyperparathyroidism and the development of cortical striation. The intracortical tunnels are proposed as an important sign for the early diagnosis of renal osteodystrophy.