Using a Protection Motivation Theory (PMT) framework, this study examined whether factual colon cancer information is a meaningful source of exercise motivation for relatives of patients with colon cancer. One hundred sixty-six inactive relatives were randomly assigned to one of two treatment conditions: PMT group (intervention); and non-PMT group (attention control). At baseline (T1) participants completed demographic information, a questionnaire designed to assess their beliefs toward exercise and colon cancer as well as their exercise intentions. At T2 (one week following T1) participants watched one of two DVD videos that were created for the study. The intervention DVD contained exercise and colon cancer information that was yoked within the four major components of PMT: perceived vulnerability (PV); perceived severity (PS); response efficacy (RE); and self-efficacy (SE), while the attention control DVD contained general diet and cancer information. Immediately following watching the DVD, participants completed the same measures as in T1. Participants assigned to the PMT intervention group showed significant improvement in PV, RE, SE and exercise intentions, whereas participants assigned to the attention control group showed significant improvement only in RE. RE, SE, and PS made significant and unique contributions to prediction of exercise intention. Overall, the results of the present study demonstrate that a single exposure media intervention grounded in a PMT framework can change individuals exercise and colon cancer beliefs, as well as change their exercise intentions. Implications of these findings and direction for future research are discussed.