In a large population-based study of Iran, the age-standardized prevalence of osteoporosis was 24.6% in men and 62.7% in women aged ≥ 60 years. Osteoporosis was negatively associated with body mass index in both sexes, and with diabetes in men and hypertriglyceridemia in women.Purpose Population aging has made osteoporosis and osteoporotic fractures an important health problem, especially in developing countries. This study aimed to explore the prevalence of osteoporosis and associated factors among the elderly population of the south-west of Iran. Methods Baseline data of the second stage of the Bushehr Elderly Health program was used. Spinal, total hip, or femoral neck osteoporosis was described as a BMD that lies 2.5 standard deviations or more, below the average values of a young healthy adult in the lumbar spine, total hip, or femoral neck, respectively. Osteoporosis at either site was defined as total osteoporosis. Agestandardized prevalence of osteoporosis was estimated. We used the modified Poisson regression with a robust variance estimator to identify the factors related to osteoporosis, adjusting for potential confounders. Results Overall, 2425 individuals (1166 men) aged over 60 years were included. In all, total osteoporosis was detected in 1006 (41.5%) of the participants. Using the reference value derived from Caucasian women aged 20-29 years, the age-standardized prevalence of total osteoporosis was 24.6 (95% CI: 21.9-27.3) in men, and 62.7 (95% CI: 60.0-65.4) in women. In men, osteoporosis was positively associated with age, smoking, history of fracture, and history of renal/liver diseases and negatively associated with body mass index (BMI) and diabetes. BMI, hypertriglyceridemia, and education were negatively correlated with osteoporosis in women, while years after menopause and history of fracture increased the likelihood of osteoporosis, significantly. Conclusion Results support the high prevalence of osteoporosis and osteopenia in the elderly population. Considering the importance of severe complications, especially fractures, comprehensive interventions should be expanded.