Background: Osteoporosis can be delayed by providing accurate and adequate information to people at risk. Therefore, we aimed to determine the knowledge, attitude, and behavior levels of women in the postmenopausal period, which is the largest group at risk. Methods: The study was conducted in a tertiary Training and Research Hospital between 1 December 2018 and 1 May 2019 in 225 postmenopausal women who applied to the Family Medicine outpatient clinic and bone mineral density (BMD) outpatient clinics for BMD measurement or had previously had this measurement at least once. A questionnaire evaluating the knowledge, attitudes, and behavior levels related to osteoporosis was applied to all patients included in the study. Results: The mean age was 58.05±9.1 years. The median osteoporosis knowledge score was 7 out of 19 points. A total of 119 (52.9%) had low knowledge scores and 106 (47.1%) had higher knowledge scores. Of the individuals with high scores, 40 (37.7%) were smoking, 64 (60.4%) did not sunbathe, 89 (84%) did not consume the recommended daily amount of calcium, and 58 (54.7%) were not exercising in the recommended time. It was seen that those who were university graduates, who had previously learned about osteoporosis from a health professional, and who had a family history of osteoporosis had higher knowledge levels. Conclusions Even in postmenopausal women who are aware that they are in the risk group and that they should have BMD, their knowledge, attitude, and behavior levels on osteoporosis were found to be quite low.