Abnormalities in circulating lipoprotein concentrations are a characteristic finding in patients undergoing dialytic therapy. A substantial number of these patients display type IV hyperlipoproteinemia. Certain data suggest that secondary hyperparathyroidism may induce disturbances in lipid metabolism. To evaluate the effects of pulse calcitriol therapy on the lipid profile in these patients, we undertook a prospective study in 12 patients on stable bicarbonate hemodialysis. Lipid parameters comprising cholesterol and the low- as well as the high-density lipoprotein subfractions, triglycerides, apolipoproteins A and B, serum parathyroid hormones (iPTH), alkaline phosphatase, calcium, phosphorus, hematocrit, and blood urea were obtained prior to commencement of pulse calcitriol therapy and again 8-10 weeks later. Calcitriol therapy was associated with a decrease in serum iPTH levels (701 +/- 103.9 vs. 220.3 +/- 50.5 pmol/l; p < 0.001). Significant increases in high-density lipoprotein cholesterol (32.8 +/- 2.7 vs. 38.8 +/- 2.3 mmol/l; p < 0.05) and apolipoprotein A-I (107.8 +/- 6.1 vs. 121.8 +/- 5.8 g/l; p < 0.05) were noted during the course of the study. Moreover, serum iPTH correlated inversely with high-density lipoprotein cholesterol and apolipoprotein A-I. There were no changes in other lipid parameters except for low-density lipoprotein cholesterol which showed a tendency to increase. We conclude that in short-term study, pulse oral calcitriol therapy is associated with an improvement in the lipid profile in patients with secondary hyperparathyroidism. However, it remains to be established whether ameliorating the uremic dyslipidemia results in any long-term clinical benefits.