The aim of the study was a comparative analysis of bone scans in uremic patients treated with intermittent peritoneal dialysis (IPD) or hemodialysis (HD). Bone scintigraphy was performed using technetium Tc 99m etidronate (EHDP) in 28 uremics (age 46.0 +/- 13.5 years, x +/- SD) on IPD for 3.1 +/- 3.0 months and 28 uremics (age 43.5 +/- 11.6 years) on HD for 47.3 +/- 33.9 months. Serum c terminal parathormone (cPTH) exceeded 5.3 +/- 3.3 and 6.8 +/- 3.5 times the upper normal limit of 1.4 ng/mL in IPD and HD patients, respectively. Despite significant differences in dialysis treatment duration in IPD and HD patients, an increased Tc 99m EHDP uptake in bones was shown with similar frequency, when all the groups were compared. However, in the group of patients with serum cPTH exceeding four times the upper normal limit (n = 30) or in the age group less than 45 years old (n = 26), a greater marker uptake was observed in HD patients. Significant differences (p < 0.05) were shown in the cranial vault: 33% of HD patients (n = 18) with higher cPTH and 47% of those less than 45 years old (n = 15) revealed an increased marker uptake, whereas it was not observed in any IPD patient. When scans of HD patients dialyzed less than (n = 11) and more than (n = 17) 30 months were compared, a significantly higher appearance of increased marker uptake was shown in cranial vault (41% vs 0%, p < 0.02) and in sacral bone (82% vs 36%, p < 0.02) in patients with longer dialysis. The latter group of HD patients also showed an increased marker uptake in cranial vault compared to the entire group of PD patients (41% vs 7%, p < 0.01). Our studies suggest that bone scan changes, indicating secondary hyperparathyroidism, progress significantly with prolongation of dialysis treatment, especially in patients with higher cPTH levels of younger age.