Background: We have investigated variations in the C-reactive protein levels in groups of patients with left ventricular dysfunction of various causes. Materials and Methods: We have studied 59 patients (ranging from 40 to 80 years, mean age of 64, SD 9) with left ventricular dysfunction caused by dilated cardiomyopathy, valvular heart disease, chronic ischemic cardiomyopathy. These patients have been compared to 30 healthy subjects and to 15 others with acute myocardial infarction. The Creactive protein levels have been analyzed and correlated to echocardiographic index of the left ventricular function as well as to the clinical parameters. Results: the levels of C-reactive protein show a statistically significant difference between healthy controls and patients with chronic left ventricular dysfunction (0.95mg/l +-0.9 vs 10.17+-13.77; p < 0.0001); a statistically significant difference between patients with chronic left ventricular dysfunction and patients with acute myocardial infarction (10.17mg/l+-13.7 vs 30.78 & [plus;-22.53, p < 0.0001), and a statistically significant difference between the group of patients with chronic left ventricular dysfunction of both ischemic and non ischemic origin (15.39mg/l +-18.19 vs 6.83+-8.77, p = 0.0095). When all chronic patients were analyzed together, the levels of C-reactive protein correlated with the New York Heart Association class (r = 0.282, p = 0.015), age (r = 0.231, p = 0.039) and with the end diastolic volume of left ventricle (r = - 0.230, p = 0.040). Conclusions: as shown by increment of C-reactive protein values, the immune system is activated in patients with the chronic left ventricular dysfunction. The patients with the chronic left ventricular dysfunction of an ishemic origin have higher levels of C-reactive protein than those of a non-ischemic origin. This difference could depend on the atherosclerotic process present presumably only in the first group.