Abstract: AIM and BACKGROUND: Osteoporosis is a health growing problem among senile .About 25 millions of people in the USA are suffering from osteoporosis who are dominantly women .The probability of women to men ratio is 5 to 1. There are more than 1.5 millions bone fractures because of osteoporosis that 300000 of them are at hip, 200000 at wrist and 500000 at vertebrae column. Hip fracture has the highest mortality and morbidity rate. At the first year the risk of death among the osteoporotic patients with hip fracture is about 10-15 percent more than the same healthy group. The treatment of osteoporotic fractures expenses about millions of dollars. The aim of this study was frequency assessment of femoral neck fractures due to osteoporosis at 19 hospitals in Tehran. These hospitals were selected according to cluster sampling method on all Tehran areas. During 1380, 942 patients with femoral neck fracture were examined. About 72 percents of them (679patients) had fracture by a small trauma because of osteoporosis. MATERIALS and METHODS: This is a cross sectional descriptive study. After randomized selection of hospitals, the researchers went to the hospitals every other week and examined the patients and filled in all the questionnaires. REULTS and DISCUSSIONRES: The average age of the patients with femoral neck fracture was 59.9 years. The average length of stay at hospital was 11.04 days. That was about 10.22 days in osteoporotic fractures and about 13.16 days in non-osteoporotic fractures. The cost of femoral neck fracture was in average 3,181,186 Rails per case in governmental hospital. That will be 4 times more at private centers. The overall mortality rate was about 2.3 percent, which differed between 1.3-11.7 percent among different hospitals. The noticeable point at this study is the lower age of femoral neck fracture (59.9 y) in Tehranian population in compare with other countries (more than 65y). Considering the increase of life expectancy index to about 72 years in Iran; this would make more problems in future.