Objective: To summarize existing research on individual numeracy and methods for presenting risk information to patients. Methods: We selectively retrieved articles from MEDLINE and the "Social Sciences Citation Index". Results: Many Americans have low numeracy skills, a deficit that impedes effective health care. Approaches to risk communication vary in current practice, but how risks are presented can significantly affect both patients' risk perceptions and their knowledge. Conclusions: Adhering to some basic principles for presenting risk information to patients can improve understanding. However, different risk-communication methods may be needed for individuals with high versus low levels of numeracy.