Health literacy is basic reading and numerical skills that allow a person to function in the health care environment. Even though most adults read at an eighth-grade level, and 20 percent of the population reads at or below a fifth-grade level, most health care materials are written at a 10th-grade level. Older patients are particularly affected because their reading and comprehension abilities are influenced by their cognition and their vision and hearing status. Inadequate health literacy can result in difficulty accessing health care, following instructions from a physician, and taking medication properly. Patients with inadequate health literacy are more likely to be hospitalized than patients with adequate skills. Patients understand medical information better when spoken to slowly, simple words are used, and a restricted amount of information is presented. For optimal comprehension and compliance, patient education material should be written at a sixth-grade or lower reading level, preferably including pictures and illustrations. All patients prefer reading medical information written in dear and concise language. Physicians should be alert to this problem because most patients are unwilling to admit that they have literacy problems.