This phase-II crossover study was designed to test if the activity of erythropoietin is time dependent. Patients with chronic renal failure on hemodialysis requiring r-HuEPO to maintain adequate levels of hematocrit are eligible for the study. Patients were administered r-HuEPO subcutaneously three times per week, 50 U/kg, rounded to the nearest 2000 units. r-HuEPO will be administered until the hematocrit rises from the baseline level of 20-24% to the target level of 30-34%. This will be repeated three times, each at different times of day, either 0800, 1500 or 2200 hrs and the order of these will be randomly determined. Each patient will complete all three of the phases.
