Background: Osteoporosis (OP) is a bone condition that weaken bone over time, making it easier to break. Objectives: The study aimed to assess knowledge level about symptoms and risk factors for osteoporosis among adult women in Cairo, and to identify factors influencing their knowledge level.Method: Cross-sectional study was carried out among sample of Egyptian women aged 18 and more, living in Cairo who agree to participate and fulfill an online structured questionnaire using Osteoporosis Knowledge Assessment Tool (OKAT)Results: A sample of 414 adult women answered the on-line questionnaire with mean age (35.6 ± 10.6). All surveyed women were familiar with OP, the predominant source of information was mass media (48.3%), followed by friends (37%), academic study (32.9%), lastly from physicians (21.3%). Mean total OKAT score was 10.5 ±3.4 (0.0 – 18.0); and the total knowledge percent score was 52.3 ± 17.1 (0.0 – 90.0). Less than half of the surveyed women(41.5%) scored a percentage score (> 60% correct answer). Knowledge level had a significant association with women working status and educational level which act also as a significant predictor for the OP knowledge level.More correct answers were recorded from that receiving information from mass media, followed by doctors, academic research, lastly friends.Conclusion: Poor knowledge about osteoporosis has been identified among adult studied women in Cairo. Developing successful health education campaigns may be beneficial in improving awareness about osteoporosis and its risk factors; and consequently, adopting healthy behavior that prevents or decreases bone loss.