One of the basic complications of chronic renal failure is secondary hyperparathyroidism. The purpose of the work was an attempt at the assessment of the effectiveness of pulsating dosage of alfacalcidol as compared to daily dosage. Ten chronically dialysed patients were given for four months alfacalcidol in the mean dose 1 mcg daily, with simultaneous administration of calcium preparations and phosphorus-binding compounds. Every month the serum concentrations of total calcium and phosphorus were determined together with alkaline phosphatase activity. For another four months the same group of patients received alfacalcidol in pulsating way in dose of 0.1 mcg/kg body weight, once weekly. As compared with the period of treatment with daily doses of alfacalcidol, the change of treatment method to pulsating one caused a significant increase of calcemia as well as an evident decrease of alkaline phosphatase activity with a marked increase of phosphatemia.