In Study I, tape-recorded Structured Interviews from MRFIT were re-scored for Potential for Hostility. In Study II, Structured Interviews were obtained from a new sample of participants in the BLSA. In the BLSA the Structured Interview were expanded to include questions that dealt more directly and sampled more fully antagonistic self-descriptions, attitudes, and behaviors. Alternative measures of Agreeableness-Antagonism were already available from the BLSA sample that were used to validate scores from the expanded Structured Interview, and biomedical information on BLSA participants was used to further test the predictive utility of Antagonistic Hostility as a risk factor for coronary heart disease. Previous research had scored Potential for Hostility from the Structured Interview by examining Content, Intensity, and Style as well as a clinical judgement of Total Potential for Hostility. In the present study, Antagonistic Hostility was measured in terms of Antagonistic Style and Self-Descriptions. A total score was defined as the sum of these two components. Antagonistic Style was scored using a 5-point scale when rudeness, condescension, and disagreeableness were expressed toward the interviewer. Matched and unmatched logistic regressions were used to evaluate Antagonistic Hostility as a risk factor for morbidity and mortality outcomes. Multivariate analyses were used to control for other standard risk factors.