Introduction: This study was to investigate the associations between personal factors, health-related factors, history of fractures, and lifestyles and osteoporosis in the postmenopausal women. Methods: This study was based on a retrospective case-control study design conducted in the Phayao Hospital, Phayao Province, Thailand. The 136 menopausal women aged 40 years and older were examined for bone density with dual x-ray absorptiometry. Those who had test results less than or equal to -2.5 standard deviation when compared to the maximum mean bone mineral density of young women (T score ≤ -2.5) were classified as the case group, and those who had test results more than -2.5 standard deviation when compared to the maximum mean bone mineral density of young women (T score > -2.5) were classified as the control group. Data were collected using questionnaires. Binary logistic regression with forward stepwise (likelihood ratio) model selection was used to explore the associated factors. Results: The factors statistically related to osteoporosis were body mass index (BMI; adjusted odds ratio (OR) = 0.81; 95 % confidence interval (CI), 0.71-0.93), age at menopause (OR = 0.88; 95 % CI, 0.79-0.99), history of fractures (OR = 10.00; 95 % CI, 2.71-36.94), family history of osteoporosis (OR = 2.66; 95 % CI, 1.04-6.77), and non-consumption of foods containing legumes, dried beans, and grains (OR = 13.84; 95 % CI, 2.08-92.11). Conclusions: It is recommended that more studies should be conducted on finding the optimal BMI and on the consumption of legumes, dried beans, and grains as osteoporotic protective factors. © 2013 International Osteoporosis Foundation and National Osteoporosis Foundation.