Objective: To evaluate the relation between BMI, diabetes and thyroid diseases with osteoporosis.Methods: From 3000 subjects referred to the densitometry centers of Gorgan, 300 subjects were selected via a systematic random sampling method.Individual characteristics, Diabetes (according to Symptoms and FBS results), Thyroid diseases (according to TSH and T4 level results) and densitometry results were collected from densitometry records. Data were analyzed by SPSS and chi square, ANOVA and simple linear regression tests. A p-value less than 0.05 considered as a significant.Results: BMI mean was 28.14 kg/m2, lumbar and femoral BMD mean was 0.92 and 0.77 respectively. BMI Mean±SD in osteoporotic subjects in lumbar and femoral region was 25.94± 5.62 and 26.95±5.20.Relation between BMI and osteoporosis in lumbar and femoral region was significant but relation between diabetes and thyroid diseases with osteoporosis in lumbar and femoral region was not significant. Simple linear regression results shows that BMI was statistically significant with osteoporosis in lumbar (B: 0.013) and femoral (B: 0.004) region.Conclusion: Our finding revealed that underweight subjects are more susceptible to osteoporosis but this study could not detect any association between diabetes and thyroid disease with osteoporosis.