OBJECTIVES: The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) recommended diuretics as first-line treatment for plan participants with simple hypertension in 2003. This study evaluated initial pharmaceutical treatment for plan participants diagnosed with simple hypertension. METHODS: The authors selected Caremark plan participants from integrated, deidentified pharmacy and medical claims data who were diagnosed with hypertension between Oct. 10, 2003, and March 31, 2004. Plan participants had to be eligible for pharmacy and medical benefits one year prior and one month post diagnosis, not have a prior diagnosis for hypertension, and not be diagnosed with a comorbid condition during the 11-month period studied. RESULTS: In the month following diagnosis, 2033 plan participants filled a prescription for at least one antihypertensive drug. Most of these plan participants were treated by primary-care physicians (84.9%). The remainder were treated by either by a cardiologist (2.3%) or some other type of specialist (12.8%). Of all those studied, 41.2% were initiated on a diuretic either as monotherapy or in combination with one of the other drugs. Those starting with diuretic monotherapy represented 26.3%, while 30.9% initiated therapy with a combination of antihypertensive drugs. The remaining 42.8% were initiated on some other type of monotherapy. Of the plan participants who initiated therapy with one antihypertensive, 31.8% started with a diuretic, 21.7% with an ACE inhibitor, and 17.8% with a beta-blocker. Of those prescribed a combination of drugs, 45.2% initiated on an ARB and diuretic, 34.9% on an ACE inhibitor and diuretic. Overall, 63.69% started with generic therapies and 36.31% with a brand drug. CONCLUSION: Only a minority of plan participants diagnosed with simple hypertension, without complicating comorbid conditions, were prescribed a diuretic monotherapy.