: Osteoporosis in men is now recognized as an increasingly important public health issue. The objective of this study was to investigate Relationship between life style and bone mineral density in men. Among the 20-76 year-old men of Tehran, 325 persons from 50 clusters were randomly selected, following exclusion of people suffering from rheumatoid arthritis, thyroid disease, menstrual problem, fractures or other conditions affecting bone metabolism. All participants underwent clinical examination and lumbar and spinal densitometry using DXA method. In lumbar spine, the duration of peak bone density was between 25 and 40years old and in hip, the duration of peak bone mass was from 20 to 30 years old. Prevalence of osteoporosis and osteopenia in men older than 50 years old were 3.9% and 50%, respectively. Bone mineral density in men significantly related with Calcium & vitamin D intake, sport and smoking. Nutritional intake and physical activity has been considered to play an important role in maintaining bone mineral density. Peak bone density in 20-40 year-old population and relation with life style could be useful in policy-making for prevention of osteoporosis.