introduction: Osteoprosis is a well recognized health hazard for women who are the main group at risk.This study assessed the relative risk factors of osteoprosis in women referring to the Chamran Hospital densitometry center during the year 1386, with the aim of designing a formula to estimate the severity of osteoprosis based on its risk factors. Materials and Methods: This cross sectional analytic study used the data of outpatients (n=1047) who visited the Bone Densitometry Center of Chamran Hospital during the year 1386. Information was gathered using questionnaires, completed face to face and the cases underwent Dexa densitometry of the hip and vertebras. The data were analysed with SPSS software. Results: Of the patients, 73% were menopausal the average and standard deviation of age and weight was 54.5± (10.3), 69.5± (10.8) and the average and standard deviation of T-score of hip and lumbar spine was -1.88± (1.08), -1.04±(1.05). After assessment, the precipitating factors of osteoprosis of hip were age, menopause, time of menopause, history of fracture, history of taking calcium supplements and dosage, number of deliveries, and duration of breast feedings. The preventing factors were weight, OCPs, exercise, (p<0.05) being significant the percipitating factors in vertebras were age, menopause, time of menopause, diabetes, history of fracture, history of calcium supplement usage and dosage, number of deliveries, timing of breast feeding and the preventing factor was weight, (p=<0.05) being significant. Using the use of stepwise regression analysis, a minimal mathematical model for predicting of bone density of hip and lumbar spine was formulated. Then the mathematical model of hip in the form of clinical decision rule (CDR) was validated with less number of independent cases. Conclusion: Using the method mentioned, along with clinical findings and history, persons at risk of osteoporosis can be identified and early prevention and treatment are possible. This can also prevent unnecessary expenses of diagnostic procedures for people without the risks of osteoprosis.