Health care providers have become increasingly aware of poor patient understanding of their illnesses and their treatments. A major, increasingly recognized factor in poor understanding and compliance is the low literacy skills of 90 million Americans. This article reviews the literature on the relationship between patients' literacy skills and the literacy levels required to read educational health care materials, and applies a similar analysis to commonly used ophthalmic patient-educational materials. Understanding the relationships between patient literacy skills and health care utilization will be critical in improving the efficiency of the health care system.