Community-acquired pneumonia (CAP) and metabolic syndrome (MS) are important independent medical and social problems. At the same time, the comorbid effect of MS on the course of CAP has not been sufficiently studied. The purpose — to evaluate the additional contribution of the metabolic syndrome (MS) to dysregulation of the cardiorespiratory system in patients with moderate severity community-acquired pneumonia (CAP). Material and methods. Four groups were examined: the first control group (CG) of 35 healthy individuals, the second control group CG + MS of 14 individuals with MS but without any acute disease; the group of 62 patients with CAP, and the group of 28 patients with CAP and comorbide MS (CAP+MS). To assess cardio-respiratory regulation, ECG and impedance pneumogram were synchronously recorded for 10 minutes. Time series of consecutive cardiointervals NN and respiratory intervals Ttot were formed from this recording. Heart rate variability (HRV) and respiratory rhythm variability (RRV) were evaluated by calculation of standard deviations (SDNN, TtotSD) and variation coefficients (CVNN, TtotCV). The spectral analysis of HRV was also performed with determination of the total spectral power Ptotal, spectral power in the intervals of 0.04–0.15 Hz (PLF) and 0.15–0.40 Hz (PHF). The data are presented as median and interquartile range Me (Q1; Q3). Results. In patients with CAP and comorbid MS, the most pronounced decrease in the variability of heart and respiratory rhythms was revealed, and it was more reliably characteristic of heart rate variability. The values of variability parameters in the CAP(1) and CAP + MS(1) groups were: SDNN — 31.7 (23.1; 43.3) and 15.6 (10.8; 20.0) ms, respectively, p < 0.001, CVNN — 3.9 (2.7; 5.0) and 2.2 (1.7; 2.8) %, p < 0.001, PLF 150.8 (73.6; 272.5) and 33.9 (15.3; 81.5) ms2, p < 0.001, PHF — 167.0 (52.5; 468.7) and 22.7 (10.5; 64.4) ms2, p < 0.001. The values of variability parameters in the CAP(2) and CAP + MS(2) groups were: SDNN — 40.7 (29.5; 62.6) and 22.4 (14.7; 33.9) ms, respectively, p < 0.001, CVNN — 4.7 (3.3; 6.9) and 3.0 (2.1; 4.2)%, p < 0.001, PLF 219.4 (119.6; 443.6) and 124.5 (30.4; 195.6) ms2, p = 0.001, PHF — 371.0 (93.4; 845.0) and 67.3 (27.8; 127.9) ms2, p < 0.001. Conclusions. The presence of comorbid MS significantly aggravates functional dysregulation of the cardiovascular and respiratory systems in patients with moderate CAP.