Self-esteem and coronary-prone behavior were identified as two personality constructs related to different stress responses. It was hypothesized that in the case of low self-esteem Type A subjects the conflicting stress responses would have a particularly adverse effect on problem-solving behavior, mood, and self-perception. Subjects were 32 Type A and 32 Type B males evenly divided into high and low self-esteem groups. Half of the subjects in each group solved 10 matrix problems under high stress, half under low stress. Compared with high self-esteem Type As, low self-esteem Type As under high stress became more hostile and perceived themselves as more tense and more hurried. They also tended to make more errors. Results are interpreted as implying that low and high self-esteem Type A subjects are not psychologically homogeneous. It is suggested that the two groups may differ substantially in terms of cardiovascular risk.