As an important public health issue, patient medication non-adherence has drawn much attention, but research on the impact of mass media as an information source on patient medication adherence has been scant. Given that mass media often provide confusing and contradicting information regarding health/medical issues, this study examined the potential negative influence of exposure to health information in mass media on patients’ beliefs about their illnesses and medications, and medication adherence, in comparison with the effects of exposure to another primary medication information source, physicians. Survey data obtained from patients on blood thinner regimens revealed that the frequency of exposure to health information in mass media was negatively related to accuracy of patients’ beliefs about their medication benefits and patient medication adherence. On the other hand, frequency of visits with physicians was positively associated with patients’ beliefs about their medication benefits but had no significant relation to medication regimen adherence. The implications of the study findings are discussed, and methodological limitations and suggestion for future research are presented.