Background: Patients with cancer who are not well informed often experience dissatisfaction with care, difficulty copingwith their disease, and feelings of helplessness. Purpose: This study was designed to investigate the information needs of women with breast cancer undergoing treatment in Vietnam and the determinants of these needs. Methods: One hundred thirty women undergoing chemotherapy for breast cancer in the National Cancer Hospital in Vietnam enrolled as volunteers in this cross-sectional descriptive correlational study. Self-perceived information needs, body functions, and disease symptoms were surveyed using the Toronto Informational Needs Questionnaire and the 23-item Breast Cancer Module of the European Organization for Research and Treatment of Cancer questionnaire, which consists of two (functional and symptom) subscales. Descriptive statistical analyses included t test, analysis of variance, Pearson correlation, and multiple linear regression. Results: The results revealed participants had high information needs and a negative future perspective. The highest information needs related to potential for recurrence, interpretation of blood test results, treatment side effects, and diet. Future perspective, income level, and educational levelwere identified as determinants of information needs, explaining 28.2% of the variance in the need for breast cancer information. Conclusions/Implications for Practice: This studywas the first to use a validated questionnaire to assess information needs in women with breast cancer in Vietnam. Healthcare professionals may refer to the findings of this study when designing and delivering health education programs designed tomeet the self-perceived information needs of women with breast cancer in Vietnam.