The aim of the study was to identify risk factors for secondary hyperparathyroidism at the start and during the first year of hemodialysis. Retrospective analysis of medical records of all patients with end-stage renal disease, dialyzed at the hemodialysis center of Kaunas University of Medicine Hospital on December 2004, was performed. Biochemical data at the start, during the first year and at the end of follow-up (December 2004) were analyzed. At the start of hemodialysis elevated level of parathyroid hormone (PTH) was observed in 46 of 69 patients (67.6%), at the end of the first year in 27 of 69 patients (39.1%). In 22 of 46 patients (47.8%), who started hemodialysis with elevated PTH levels, the level of PTH decreased to <22 pmol/l after 1 year. In comparison with patients who maintained elevated PTH levels, they showed lower levels of PTH at the start of hemodialysis. Levels of serum calcium and phosphate at the start of hemodialysis did not differ between groups. At the end of the first year patients in whom levels of PTH decreased had higher serum calcium concentration as compared with those who maintained levels of PTH > or =22 pmol/l. A multivariate analysis revealed that levels of PTH and alkaline phosphatase after one year of hemodialysis were associated with increased risk for secondary hyperparathyroidism on the follow up. CONCLUSIONS Control of calcium-phosphate metabolism in the pre-dialysis period is not sufficient. Symptoms of secondary hyperparathyroidism were diagnosed in more than a half of patients starting hemodialysis. Levels of PTH and alkaline phosphatase at the end of the first year are early risk factors for secondary hyperparathyroidism on the follow-up.