Although osteoporosis prevention has been identified as a critical issue for women and the elderly population, some health professionals still misunderstand osteoporosis. Public health nurses (PHNs) are responsible for health promotion and disease prevention in community populations. The objective of this study was to investigate PHNs' knowledge of osteoporosis and its related factors. A cross-sectional research design was used: 678 subjects from 3,300 PHNs who worked at health centers in Taiwan during 2000 were selected by cluster random sampling to participate in this study; 539 of them returned the questionnaire. On average, the PHNs' knowledge was found to be 0.68 (ranging from 0 to 1). The highest and lowest scores were found in the areas of disease prevention and the detection of the symptoms/signs of osteoporosis. By using one-way ANOVA, our study found that participants who had studied osteoporosis at school, had graduated from university, were RNs or LPNs and had studied osteoporosis as part of continuing education (CE) had higher knowledge scores. This study recommends that CE and nursing education about osteoporosis need to be highly valued. Nursing educators should reassess and reconstruct nursing curricula. Health administrators should evaluate learning needs and provide CE via multiple channels. Symptoms/signs, diagnosis/treatment and prevention issues are suggested as the core components of designing nursing curricula and CE.