PURPOSE: A predominance of parasympathetic drive is observed following cold exposure. Such modulation of the autonomic nervous system (ANS) is associated with faster post-exercise recovery. Within this context, whole-body cryotherapy (WBC) has been spreading in sport medicine, though the optimal temperature and frequency are unclear. The aim of this study was to examine the effects of different cryotherapy conditions on the sympathovagal balance. METHODS: Forty healthy males were randomly assigned into five different groups (- 110 degrees C, - 60 degrees C, - 10 degrees C, control temperature [ approximately 24 degrees C]) and undertook 5 WBC sessions over 5 consecutive days. Cardiac autonomic activity was assessed through heart rate variability (HRV) using power density of high frequency (HF), root-mean square difference of successive R-R intervals (RMSSD) and sympathovagal balance (LF/HF). Systemic sympathetic activity was assessed via circulating blood catecholamines. RESULTS: Mean weekly RMSSD (pre: 48 +/- 22 ms, post: 68 +/- 29 ms) and HF (pre: 607 +/- 692 ms(2), post: 1271 +/- 1180 ms(2)) increased (p < 0.05) from pre to post WBC, only in the - 110 degrees C condition. A rise in plasma norepinephrine was found after the first - 110 degrees C WBC session only (pre: 173 +/- 98, post: 352 +/- 231 ng L(-1), p < 0.01); whereas, it was not significant after the 5th session (pre: 161 +/- 120, post: 293 +/- 245 ng L(-1), p = 0.15). CONCLUSION: These results suggest that one - 110 degrees C WBC exposure is required to stimulate the ANS. After five daily exposures, a lower autonomic response was recorded compared to day one, therefore suggesting the development of physiological habituation to WBC.