Multiple studies reveals factors that influence transplanted kidney function. We evaluated the electrolyte imbalances during the 1st year after transplantation. This is a prospective study on 100 renal transplanted patients with normal kidney function for 6 month after operation. Na, K, Ca and Ph were evaluated before and on the 1st, 3rd, 7th and 14th day after operation, and in the 1st, 3rd and 6th month follow up. PTH levels were determined before and 6th months after operation. On the 3rd and 7th days after transplantation, 32.4% and 62% of patients developed hyponatremia, and 29.6% and 37% had hypokalemia respectively. At the end of the 1st month no one had hypokalemia and 21% showed hyperka1emia. Average serum Ca level was 9.26 ±0.49 mg/dl in 1st week which raised to 9.8 ±0. 64 mg/dl (p= 0.000) 6 month later. All the patients who developed hypercalcemia, had PTH levels more than 3 times the normal values at 6 month post Op and PTH level more than 300 pg/ ml before operation. After transplantation serum PTH decreased from198.58 pg/ml to 85.78±70.75 pg/ml. Hypophosphatemia was found in 31.4% in the 1st week and in 29.2% 6th month after operation. We did not observe any relationship between hypophosphatemia and serum PTH level before and after operation. Hyponatremia and Hypokalemia are prevalent in the 1st week after renal transplantation. Serum PTH level decreased after renal transplantation in all patients. Higher serum PTH level before operation is a main factor in establishment of hyperparathyroidism after transplantation.