1087 patients were randomized to determine the difference between two vitamin D analogs on the reduction of vertebral fractures in osteoporotic patients. Enrolled patients were allocated to receive eldecalcitol or alfacalcidol once daily, and were followed for 3 years. The results indicated that eldecalcitol reduced the risk of vertebral and wrist fractures, improved lumbar spine and total hip bone mineral density and decrease serum levels of bone turnover markers compared to alfacalcidol, but was associated with increased serum and urinary calcium levels.