In this article, we show that people's evaluations of the seriousness of a health disorder are influenced by the perceived prevalence and personal relevance of that disorder. As part of a study ostensibly concerned with college students' health characteristics, 60 undergraduates were "tested" for the presence of a fictitious enzyme deficiency. The subjects discovered either that they had the deficiency (deficiency-present subjects) or that they did not have it (deficiency-absent subjects), and were led to believe either that 1 of the 5 people in the laboratory had the deficiency (low-prevalence subjects) or that 4 of them had it (high-prevalence subjects). As predicted, the low-prevalence subjects evaluated the deficiency as more serious than did the high-prevalence subjects. In addition, consistent with the view that personal relevance affects perceptions of health disorders, the deficiency-present subjects evaluated the deficiency as less serious than did the deficiency-absent subjects. The deficiency-present subjects also derogated the validity of the test ostensibly used to diagnose the deficiency compared with other subjects. Finally, the deficiency-present subjects requested more information about the deficiency than did the deficiency-absent subjects.