We prospectively investigated the effects of adding carvedilol to the standard treatment of ischemic and nonischemic dilated cardiomyopathy (DCM), by measuring the plasma levels of pro-inflammatory cytokines. Sixty patients with DCM (35 ischemic and 25 nonischemic) were divided into 2 subgroups: patients on standard therapy alone (digoxin, angiotensin-converting enzyme inhibitors, and diuretics) and patients on standard therapy plus carvedilol. Study participants' serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-2 (IL-2), and interleukin-6 (IL-6) were measured at the beginning and again at the end of the study. Left ventricular ejection fraction and left ventricular diastolic function were evaluated by means of radionuclide ventriculography. In ischemic patients on carvedilol, levels of IL-6 and TNF-alpha dropped significantly (P= 0.028 and P=0.034, respectively). In ischemic patients on standard treatment, plasma IL-2 levels were elevated after treatment (P=0.047). No significant differences occurred in IL-6 levels, while TNF-alpha levels were elevated (P=0.008). In nonischemic patients on carvedilol, IL-6 and TNF-alpha levels dropped significantly (P=0.018 and P=0.004, respectively). The left ventricular ejection fraction increased significantly (P=0.006). In nonischemic patients on standard treatment, no significant change occurred in any value. Carvedilol suppressed the plasma levels of TNF-alpha and IL-6 in both ischemic and nonischemic patients. The carvedilol effect was more pronounced in patients with nonischemic dilated cardiomyopathy than in those with ischemic disease.