Objective Information overload can negatively impact positive health behaviors such as cancer screening. The 8-item Cancer Information Overload (CIO) scale appears to be the only validated measure of health-related information overload. The present study assesses the validity of the CIO scale when modified for use in patients with atrial fibrillation (AF) residing in Australia. Methods We conducted a secondary analysis of data from a study of adult Australian patients with AF (N = 386) in which a modified version of the CIO scale was used. In the present study, we examined the construct (convergent and divergent) validity and performed an exploratory factor analysis for the modified scale. Results All items on the modified-CIO scale appear to load onto a single factor. As predicted, higher education levels (rs=-.24, p < .001) and higher oral anticoagulant knowledge (rs=-.17, p = .001) were significantly associated with lower modified-CIO scores; no other demographic characteristics were significantly associated with CIO scores. Conclusion When adapted to the AF context, the modified-CIO scale appears to be a valid measure of information overload. Practice Implications A valid scale is required to measure information overload accurately. Knowledge of the interplay between information overload and various health behaviors help focus future efforts to support patient empowerment.