Carvedilol is a beta1-, beta2-, and alpha1-adrenergic blocker that is approved for the treatment of hypertension. A new once-daily, controlled-release (CR) formulation of carvedilol has been shown to be effective in a double-blind, randomized, multicenter, placebo-controlled, parallel-group study. In this article, we summarize the primary results of, and present additional analyses from, that trial. A total of 338 patients with essential hypertension (sitting diastolic blood pressure [DBP] >/=90 and </=109 mm Hg) were randomized to receive carvedilol CR 20, 40, or 80 mg or placebo for 6 weeks. The primary objective was to compare the effects of the 3 carvedilol CR doses with placebo on 24-hour mean blood pressure using ambulatory blood pressure monitoring (ABPM). Mean DBP and systolic BP (SBP) at the drug trough (20-24 hour) blood levels for carvedilol CR and comparison of DBP and SBP at the drug peak (3-7 hour) blood levels for each dose of carvedilol CR and placebo were investigated. The effects of carvedilol CR on heart rate and pulse pressure were also examined. Once-daily administration of carvedilol CR, alone or in combination with other agents, produced clinically and statistically significant reductions compared with placebo for both DBP and SBP after 6 weeks of treatment for the following parameters: trough blood pressure by office cuff or ABPM measurements, peak blood pressure by ABPM, and 24-hour mean blood pressure by ABPM. Placebo-corrected trough-to-peak ratios for DBP were >0.6 for each carvedilol CR dose. Heart rate and pulse pressure were each significantly reduced compared with placebo for each carvedilol CR dose. We conclude that carvedilol CR is a very effective antihypertensive agent with clear dose-related peak blood pressure reduction and continuous 24-hour control.