Heart rate (HR) estimation and actual HRs were obtained from 28 Type A and 28 Type B males before and after receiving feedback about their actual HR levels, and during performance of a moderately stressful task, digit recall. Self-reports of affective arousal during digit recall were also obtained from the Anxiety scale of the Multiple Affect Adjective Check List (MAACL) and a self-report questionnaire measuring affective reactions. Type As showed significantly higher HR increases during the digit recall than did Type Bs. Type As also reported significantly more affective reactions than Type Bs on the self-report questionnaire, but not on the MAACL Anxiety scale. Type As significantly overestimated their HRs relative to Type B at rest before receiving feedback, and during the digit-recall task. These results contradict the usual assumption that Type As underestimate their arousal levels.