In order to determine whether a hostile attitude is associated with hypertension in post-menopausal women, we conducted a cross-sectional study of a sample of post-menopausal women enrollees from the Group Health Cooperative (Seattle, Washington). Out-patient medical records were reviewed for all subjects. Hypertension was defined as a recorded diagnosis of hypertension and treatment with an anti-hypertensive drug. Borderline hypertensives were excluded. Women were interviewed by telephone and asked the 14 questions comprising the Hostile-Affect (HOS) and Aggressive-Responding (AGGR) factors of the Cook-Medley hostility scale. Scores were grouped into high vs low HOS and AGGR. The AGGR score was available for 430 hypertensives and 628 normotensives. The HOS score was available for 436 hypertensives and 616 normotensives. High AGGR scores had a borderline association with hypertension (Odds Ratio (OR) = 1.26; 95% Confidence interval (CI) = 0.97-1.62). HOS was not associated with hypertension. Adjusting for age, physical activity, diabetes mellitus, cholesterol level, tobacco and alcohol use, weight and race, changed the association of AGGR with hypertension only slightly (OR = 1.22; CI = 0.92-1.63). We found a weak association between the prevalence of treated hypertension and AGGR in post-menopausal women. There was no association between the HOS component and hypertension. The results of this study support the need for prospective studies of the role of psychological factors in the development of hypertension in post-menopausal women. If this association is confirmed, AGGR measures may help identify women at high-risk who are most likely to benefit from hypertension screening and primary prevention.