Clinical physiological monitoring of 32 men aged 25-60 years with chronic stoneless cholecystitis in the phase of remission found that in 14 patients 75-85 minutes after drinking the bioactive water Naftussya (3 ml/kg, t(0) 18-20 degrees C) the plasma level of total triiodothyronine (T3) was not significantly changed, while in 9 patients it was reduced to 0.26 +/- 0.10 nM/1 (by 11%). In the other 9 patients the level increased to 0.29 +/- 0,04 nM/1 (by 17%). The changes in T3 level correlated negatively with the changes in absolute (r = -0.55) and relative (r = -0.47) power spectral density (PSD) of ultra very low-frequency components of heart rate variability (HRV). These changes correlated positively (r = 0.46) with the changes in relative PSD of low-frequency components of HRV. Subject to a weak correlation with HRV parameter pNN50 (r = -0.21) canonical correlation coefficient (R) between changes in HRV parameters and T3 reaches 0.68 (p = 0.002). On the other hand, the changes in T3 correlated with its initial level (r = -0.46), as well as initial levels of moda (r = -0.40), its amplitude (r = 0.30) and absolute PSD of low-frequency components HRV (r = -0.33), i.e. thyrotropic effects conditionized these parameters by 30% (R = 0.55; p = 0.038). The method ofdiscriminant analysis has identified 14 primary parameters that allowed predicting the thyrotropic effect of Naftussya water with 100% accuracy.