Although the benefits of antihypertensive drugs have been clearly established, they remain underused by vulnerable older populations. We examined whether the presence of noncardiovascular comorbidity deters use of antihypertensives in elderly with hypertension. We conducted a retrospective cohort study among 51,517 patients > or =65 years of age in the Pennsylvania Pharmaceutical Assistance Contract for the Elderly (PACE) Program during 1999 and 2000. All were hypertensive and had diagnoses and used treatments during 1999 to qualify for entry into 1 of the following 5 mutually exclusive cohorts: asthma/chronic obstructive pulmonary disease (COPD), depression, gastrointestinal (GI) disorders, osteoarthritis, or none of the 4 comorbidities. Proportions using antihypertensives in 2000 were assessed. Logistic regression analysis was used to identify the independent effects on antihypertensive use of the 4 comorbidities of interest, sociodemographic characteristics, other cardiovascular and noncardiovascular comorbidity, and health care utilization variables. After adjustments in multivariable analyses, antihypertensive use was consistently lower in patients with asthma/COPD (odds ratio [OR], 0.43; 95% confidence interval [CI], 0.40 to 0.47), depression (OR, 0.50; 95% CI, 0.45 to 0.55), GI disorders (OR, 0.59; 95% CI, 0.54 to 0.64), and osteoarthritis (OR, 0.63; 95% CI, 0.59 to 0.67) relative to those without these conditions. Reduced antihypertensive use was also associated with older age, female gender, white race, more severe other comorbidities, absence of some cardiovascular indications, hospitalizations, nursing home care, physician visits, and use of fewer other medications. Highly prevalent, noncardiovascular conditions appear to deter use of antihypertensives in elderly with hypertension.