Approximately 50 million people have hypertension. Many agents with differing efficacy, side effects, dosing schedules, and costs are available to treat hypertension. Joint National Committee (JNC) guidelines attempt to simplify this decision by recommending specific agents based on special considerations such as comorbidities. The objective of this study was to survey primary care physicians' antihypertensive prescribing practices and their treatment recommendations for patients with comorbidities. A direct mail survey was sent to a national random sample of 500 office-based primary care internists, family practitioners, and general practitioners. There were no significant differences between initial treatment recommendations at the time of the survey and those recommended before the survey. However, there were several therapeutic classes whose reported utilization for specific comorbidities significantly changed over 18 months. Angiotensin converting enzyme (ACE) inhibitors reportedly increased in patients with congestive heart failure and diabetes. In addition, the reported use of selective beta-blockers increased for patients with a history of myocardial infarction. Physicians did not follow JNC recommendations when initiating treatment in black patients, older patients, or those with mild renal failure. Younger physicians were more likely than older physicians to select agents consistent with guideline recommendations. Physicians did not adhere to JNC guidelines when initiating treatment in patients with comorbidities; however, more physicians are prescribing recommended agents today as compared to 18 months ago. Younger physicians were more likely to prescribe agents consistent with the guidelines. More direct efforts are needed to ensure awareness and compliance with these guidelines.