Background: osteoporosis is considered as a major worldwide health problem. Little is known about its definition, risk factors and prevalence in Kingdom of Saudi Arabia (KSA). Objectives: Evaluating the general knowledge of Saudi females in Riyadh about osteoporosis. Subjects and Methods: this was an analytical and descriptive study. A reliable osteoporosis knowledge assessment tool (OKAT) questionnaire was published online for considering the levels of osteoporosis awareness from February 2017 to July 2017. Results: The majority of females were educated, married, had college degree and living in medium economic state. Only ten patients reported having osteoporosis. The majority of participants (%) had high OKAT score indicating high prevalence of good knowledge among included subjects. The young age, being highly educated and good economic status were significantly associated with good awareness. Conclusion: a good level of knowledge about osteoporosis was found among included subjects. Although having good awareness about osteoporosis in Riyadh, the majority of subjects obtained their knowledge from relatives and physicians. Thus, authorities should create educational programs at all health care facilities to assess a preventive programs for osteoporosis.