Cancer is the leading cause of death in Taiwan. Breast cancer has the highest morbidity rate in females. Early detection in Taiwanese women is hampered by their inadequate knowledge of risk factors, their biased perceptions of mammography and by their low intentions to carry out recommended preventative strategies. Although the Internet has become a powerful tool to disseminate health information, health information offered on the web frequently is not theoretically-based or patient-centered. Effken's (2003) Informatics Research Organizing Model (IROM) and the Transtheoretical Model (TTM) (Prochaska & Diclemente, 1982; Rakowski, Dube, & Goldstein, 1996) were used to guide the design and evaluation of a tailored web-based program aimed at improving effective breast cancer detection in Taiwanese women. This study used a pretest-posttest design to examine the impact of a tailored, web-based educational intervention on Taiwanese women's perceptions of and intentions to obtain mammography, as well as their satisfaction with the website. One hundred twenty eight Taiwanese women were randomly assigned to one of two groups: tailored intervention (TI) or standard intervention (SI). The TI group received tailored educational materials (i.e. tailored messages, case studies, personal testimonies, and mammography information). The SI group received an educational brochure developed by the Bureau of Health Promotion, Department of Health (DOH). A Stage of Adoption of Mammography Question (SAMQ) and Decisional Balance of Mammography Inventory (DBMI) were administered before and after the educational intervention. A Website Users Satisfaction (WUS) and Demographics Inventory (DI) were administered after the intervention. All materials and instruments were delivered and assessed via a website. ANCOVAs, Chi-Square tests and t-tests were utilized to test the hypotheses. Results of the study revealed that the TI group differed significantly from the SI group in terms of perceptions of, and intentions to obtain, mammography, as well as in satisfaction with the website. The results of this study contribute to our knowledge of how a health education website can change women's mammography-related perceptions and intentions if theoretically-based and tailored interventions are emphasized.