PURPOSE: The purpose of this study was to estimate the morbidity and mortality rate of bilateral hip fractures in elderly patients compared to that in unilateral hip fractures and to evaluate it's related risk factors. MATERIALS AND METHODS: Twenty-two cases of bilateral hip fractures in patients who were older than 70 years with at least two year follow-up were included in our study. We analysed the risk factors of bilateral hip fractures by comparing with age, sex and diagnosis matched 22 cases of ipsilateral hip fractures including onset of secondary fracture, injury mechanism and the rate of morbidity and mortality, respectively. RESULTS: The onset of secondary fracture and death were mostly within 1 year after operation for the first hip fracture. Comorbidity of cardiovascular, neurologic, urologic or history of previous fracture and decreased ambulation ability were related with the occurrence of bilateral hip fractures. The rate of morbidity and mortality of bilateral hip fractures were about two- fold than that of ipsilateral hip fractures. High mortality rate was noted in patients who had operation delay from injury. But no significant relationship between nutrition, body weight or bone mineral density and the development of secondary hip fractures. CONCLUSION: To prevent the occurence of bilateral hip fractures which had more serious results than that of ipsilateral hip fractures, more aggressive rehabilitation to improve walking ability and appropriate environmental circumstances to avoid falls were important, especially in older patients.