We and others have previously shown that carvedilol improves left ventricular (LV) function and symptoms in chronic heart failure. This improvement in LV function has also been shown to be associated with an improvement in survival. This study evaluates the effect of carvedilol on LV mass, geometry, and degree of mitral regurgitation (MR). In 59 patients with symptomatic heart failure and LV ejection fraction <0.35, previously randomized to either treatment with carvedilol or placebo, we evaluated LV mass, geometry, and degree of MR over the time period of carvedilol treatment. LV mass decreased as early as 4 months into the treatment protocol and continued to decrease over a period of 1 year. LV geometry, defined by the length/diameter ratio, and severity of MR also improved with 4 months of therapy. Thus, compared with placebo treatment, carvedilol decreases LV mass while improving cardiac geometry and decreasing MR in patients with chronic heart failure. These changes occur in association with an improvement in LV systolic function. This process begins by 4 months of treatment and continues for 12 months.