It's reported a case of progressive and rapid deterioration of the renal function, following to a wrong administration of high doses of recombinant erythropoietin. After the administration of 10,000 U of rHuEPO three times a week for at least five times instead of the 1000 U ordered, the patient showed a progressive increase of the plasmatic creatinine values from 2.2 to 3.3 mg/dl. In the same period we pointed out an increase of hematocrit (from 29% to 35%) and of the Hb (from 9.3 to 11.2 g/dl). The patient, suffering from a slightly high blood pressure, furthermore showed important pressure increases. The suspension of the treatment by erythropoietin permitted the restoration of the creatinine values to levels similar to the ones pointed out before the treatment and a reduction of the blood pressure values. The AA. think that a too rapid regression of the anaemia achieved by a rHuEPO treatment can condition a worsening of the renal function in the pre uraemic patient.