Background. Disorders of endogenous rhythmicity are closely associated with the mechanisms of general adaptation syndrome, i.e., stress. Meanwhile pain, which is one of the most common causes of stress response, can induce considerable alterations in the activity of the autonomic nervous system. On the basis of the contemporary view of pain, stress and biological rhythms, we suggested that the responses of the circadian and ultradian rhythmicity of heart rate may differ depending on the type of analgesia in case of a surgical intervention. Objectives. Specific features of the 24-hour profile of heart rate in patients who underwent tonsillectomy under different types of analgesia were studied in this work. Subjects and methods. The study included 54 adults and was approved by the Ethic Committee of the RUDN University Institute of Medicine. The patients with chronic tonsillitis underwent tonsillectomy either under local or under general anesthesia. Control group was presented by healthy non-patient volunteers. All the participants underwent 24-hour Holter monitoring of ECG with 3-channel MT-101 Holter recorders and Software MT-200 (Schiller, Switzerland). The further processing of data was performed using software “Chronos-Fit”: By linear analysis the following indices were obtained: Mean daily, mean daytime, mean nighttime heart rate and circadian index; on the basis of non-linear analysis the calculated parameters were: Maximum and minimum heart rate over 24 hours, range of oscillations, MESOR, amplitude and power of oscillations. Results. In the group of patients who were operated on under general anesthesia HRmax, HRmin, MESOR and range of oscillations were significantly lower compared with the controls and with the group of local anesthesia. At the same time in the group of general anesthesia we observed a considerable increase in % rhythm (power of oscillations) in comparison with the group of local anesthesia. Conclusion. General anesthesia has a stronger effect on the mechanisms regulating chronotropic function of the heart and more positive influence on the biorhythmological properties of heart rate compared with local anesthesia in case of tonsillectomy. © 2019 Nova Science Publishers, Inc.