AIM: To evaluate parameters of variation pulsometry, heart rate variability (HRV) before and after surgical treatment of patients with thyrotoxicosis. MATERIAL AND METHODS: Enzyme immunoassay measured blood levels of TTH and free thyroxin (T4f), HRV was traced for 5 min with variation pulsometry, frequency and time course analysis in 124 patients (37 males, 87 females, age 20-74, mean age 50.4 +/- 1.7 years) with manifest (n = 73) and complicated (n = 51) thyrotoxicosis in diffuse (n = 36) or multinodular (n = 88) toxic goiter before and 7 days after thyroid resection. RESULTS: Aggravation of thyroxinemia with progression of thyrotoxicosis was accompanied with sympathicotonia change for vagotonia showing depletion of adaptive mechanisms in a complicated form of the disease. The weaker was sympathicotony in manifest thyrotoxicosis and the stronger was parasympathetic tension in complicated thyrotoxicosis, the higher were SDNN, RMSSD, TF, HF and LF/HF. Early after surgery (thyroid resection) thyrotoxicosis relieved with attenuation of thyroxinemia, vegetative regulation rearranged for adaptation up to achievement of vagosympathetic balance. This was more frequent in a manifest (56.1%) than in a complicated form of the disease (41.1%). CONCLUSION: HRV provides an objective assessment of the effects of surgical treatment on the status of the autonomic nervous system.