By the time patients require dialysis replacement therapy, nearly all chronic kidney diseases (CKD) patients are affected with uremic bone diseases. High-turnover osteodystrophy can be prevented; patients with CKD should be monitored for imbalances in calcidiol (25 OH vitamin D), calcium, and phosphate homeostasis. We aimed to determine the effect of a monthly oral 300,000 IU vitamin D-3 (cholecalciferol) supplementation on the uremic bone diseases (UBD) markers such as iPTH and alkaline phosphatase in CKD patients. Among a total of 70 patients under treatment in the nephrology unit, 40 predialysis CKD patients (mean age of 49 14, male/female 20/20) were included the study. The patients were randomly divided into two groups. Treatment group included 20 patients (mean age of 51 +/- 14, male/female 9/11), and the control group comprised 20 patients (mean age of 47 +/- 14, male/female 9/11). Treatment group patients were given a single dose of Devit3 ampoule (300,000 U cholecalciferol) per month orally way. Patients in the control group did not take any vitamin D for a month. The level of calcidiol was lower than normal range in two groups. After a month, treatment group patient's calcidiol increased statistically significant (6.8 +/- 3.5 to 17.8 +/- 21.4 ng/mL, p < 0.001). After a month, iPTH level decreased in the treatment group statistically significantly (368 +/- 274 to 279 +/- 179 pg/ml, p < 0.001). At the 30(th) day of the treatment, in 9/20 of the treatment group patients (45%), the iPTH value decreased at least 30% (p < 0.001). We suggest that oral depot cholecalciferol treatment causes a statistically significant decrease of serum iPTH level but does not cause a statistically significant change in Ca, P, ratio of CaxP, or urinary calcium creatinine rate in UBD predialysis CKD. This treatment can be used safely for the predialysis CKD patients, along with the cautious control of serum calcium and phosphor.