BACKGROUND Consent forms are required in most biomedical research involving human subjects. In recent years, a number of studies from different disciplines have reported problems related to consent form readability. METHODS We analyzed 284 consent forms submitted to and approved by five institutional review boards (IRBs) (schools of Medicine, Nursing, Academic Affairs, Dentistry, and Public Health) at one university and one IRB at another. We examined consent form readability scores and factors that might relate to readability. RESULTS The average reading level of all consent forms was high: 12.2, which corresponds roughly to a 12th-grade reading level. Less than 10% of all consent forms were written at a 10th grade reading level or below. Thirty-two percent of all consent forms had no evidence of revisions, and less than 2% of consent forms were revised more than once. Readability scores were not related to consent form revisions, the type of IRB, the year of study, or the university where the research was conducted. CONCLUSIONS Poor readability of consent forms probably occurs in all university-related research. We recommend that IRBs require readability checks for research consent forms before researchers submit their proposals to an IRB.