This research investigated perceived medical noncompliance between obese and hypertensive patients. An illusory correlation formed between obese patients and their noncooperative behaviors. Participants overestimated the frequency with which obese patients did not cooperate with their physician's advice when these patients appeared infrequently. When hypertensive patients appeared infrequently, however, participants were accurate in their estimates of noncooperation for these patients. These findings suggest that stigmatized patients suffer more from an illusory correlation bias than do nonstigmatized patients, and this effect is exacerbated when people have infrequent contact with stigmatized patients.