Decreased bone mineral density is a common problem after kidney transplantation and osteoporosis has a major role in morbidity of these patients. This study was performed to evaluate the frequency of osteoporosis and determination of its risk factors. Renal transplanted patients who were between 17 and 50 years old and transplanted between 6 months to 2 years ago were included. Bone mineral densitometery(BMD) was performed by DEXA. Seventy-seven patients were enrolled. Frequency of osteoporosis was 26%(20/77). Mean age was 34.6±8.7. The most common site of osteoporosis was hip. 19 out of 77 BMD performed on hip were osteoporotic(24.7%) and 42 were osteopenic(54.5%). In spine 7.8% were osteoporotic, 67.5% were osteopenic. There was significant relation between post transplant creatinine (at the study time) and osteoporosis of hip (P=0.01). No relations were found between osteoporosis and age, sex, BMI, hemodialysis duration and cumulative dose of any drugs or methylprednisolone pulses. Z-scores <-1 in hip or spine had no relation with numbers of methylprenisolone pulses but had significant relation with total dose of cyclosporine A(p<0.001), prednisolone(p<0.001) and cellcept (p<0.05). Z-scores under -1 in hip was related with post transplants days (p=0.02).In conclusion, Osteoporosis is a frequent complication in this study. Detection and treatment of patients, who are in danger, may decrease the morbidity of osteoporosis.