Aim. To study the specific features of an immune response and the role of infectious pathogens in the occurrence, development, and maintenance of ventricular ectopic activity in patients without signs of organic disease of the cardiovascular system (CVS). Subjects and methods. The investigation enrolled 91 patients (27 men and 64 women with a mean age of 36.5±11.5 years) with premature ventricular contractions (PVC) without signs of organic CVS pathology. A control group comprised 31 healthy volunteers. In addition to standard physical examination, a study of N-terminal pro-brain natriuretic peptide (NT-proBNP) and cellular and humoral immune parameters was performed and the serological and molecular genetic markers of infections were determined in all the patients. Results. The persons with PVC, as compared to the control group, were recorded to have a higher NT-proBNP level (49.2 pg/ml versus 25.4 pg/ml; p=0.001) accompanied by an increase in both the total number of PVC and the number of coupled PVC and the episodes of ventricular tachycardia. They were also found to have elevated CD3+HLA-DR+ (2.4% versus 1.56%) and CD3+CD95+ (27.6% versus 18.8%) counts (p=0.001). In patients with a C-reactive protein level of more than 2 mg/l, the total number of PVC was larger than that in the other patients (p=0.065). The patients with PVC did not show a statistically significant difference from the controls in the levels of antiviral and antibacterial antibodies. The people with PVC displayed a number of relationships between the infectious pathogen antibody titers and the ECG Holter monitoring and echocardiography readings. Conclusion. In the patients with PVC without signs of organic CVS pathology, the parameters of an immune response were not different from those obtained in the control group, which was likely to be associated with the involvement of the immune system in the development and maintenance of ventricular arrhythmias.