The work is devoted to the study of the effect of Staphylococcus aureus peptidoglycan on the main parameters of myometrial contractions and the mechanism of this influence. The research was carried out by tensometry and calcimetry methods. The results of the experiments demonstrated that peptidoglycan modulates all the main parameters of contractions of the non-pregnant rat uterus, including increasing their amplitude and duration by 10 and 30%, respectively, mainly by prolonging the relaxation phase (56.7 ± 1.6%): myometrial band relative to quickly shrunk and relaxed for a long time. Application of peptidoglycan on freshly isolated uterine myocytes for 5 min led to a periodic increase in their intracellular content of calcium ions. Peptidoglycan enhanced myometrial contractions caused by hyperpotassium solution at a concentration of 60 mmol. Administration of 1 μmol of nifedipine, a blocker of potential-directed L-type calcium channels, suppressed spontaneous contractions enhanced by peptidoglycan. These changes in myometrium contractility of on the background of peptidoglycan action occur not only due to increased transmembrane calcium intake, but also its mobilization from the sarcoplasmic reticulum.