Interruption of sympathetic outflow by surgical sympathetic block has been used to treat hyperhidrosis for decades. In this study the effect of gender and the level of sympathetic block (T2 vs. T3) on the rewarming kinetics following ice water immersion were assessed in a prospective study on 60 hyperhidrosis patients before, 2 days, and 3 months postoperatively. Rewarming kinetics following endoscopic sympathetic block (ESB) was massively enhanced 2 days post-operatively, but had returned to pre-operative conditions at the 3 month follow-up for ESB at level T3. ESB at level T2 provoked significantly faster rewarming as compared to T3 at the 2 day and 3 month follow-up. Independent of the level of ESB, there was a slower rewarming in women already pre-operatively. This gender difference was clearly reduced at the 2 day follow-up, but had increased again at the 3 month follow-up. There was no correlation between the rewarming kinetics of the fingertips and palmar sweating. We conclude that for the sympathetic vasoconstriction of the fingertips the sympathetic ganglion T2 is crucial. Gender differences have to be taken into account when assessing effect of ESB by cold induced vasoconstriction. It remains to be established whether the quantification of vasoconstriction has some predictive value for the long-term prognosis of sudomotor blockade.