This study evaluates the Brief Illness Perception Questionnaire (Brief IPQ), a nine-item scale designed to rapidly assess the cognitive and emotional representations of illness. We assessed the test-retest reliability of the scale in 132 renal outpatients. We assessed concurrent validity by comparing the Brief IPQ with the Illness Perception Questionnaire-Revised (IPQ-R) and other relevant measures in 309 asthma, 132 renal, and 119 diabetes outpatients. Predictive validity was established by examining the relationship of Brief IPQ scores to outcomes in a sample of 103 myocardial infarction (MI) patients. Discriminant validity was examined by comparing scores on the Brief IPQ between five different illness groups. The Brief IPQ showed good test-retest reliability and concurrent validity with relevant measures. The scale also demonstrated good predictive validity in patients recovering from MI with individual items being related to mental and physical functioning at 3 months' follow-up, cardiac rehabilitation class attendance, and speed of return to work. The discriminant validity of the Brief IPQ was supported by its ability to distinguish between different illnesses. The Brief IPQ provides a rapid assessment of illness perceptions, which could be particularly helpful in ill populations, large-scale studies, and in repeated measures research designs.