BACKGROUND: Recently a report was published about the cross-inhibitory effect of post ganglionic neuron between upper extremities. We tried to find the existence of the same effect in all extremities by comparing the changes of skin temperature (ST) of all extremities during and after sympathicotomy for palmar hyperhidrosis. METHODS: Twenty patients with palmar hyperhydrosis underwent bilateral video-assisted thoracoscopic sympathicomy. Right side T3 sympathicotomy was performed first, then left side T3 sympathicotomy was done. The ST of both hands and feet were compared with the ST before the surgery at 2, 4, 6, 10 minutes after first (right) sympathicotomy, 10 minutes after second (left) sympathicotomy and 4 hours after both sympathicotomy in the post anesthetic care unit (PACU) of our one-day surgery center. RESULTS: At 10 minutes after completion of first (right) sympathicotomy, ipsilateral increase of the ST (right hand, 2.73 +/- 2.01oC) and contralateral decrease of the ST (left hand, - 0.65 +/- 0.88oC) were observed (P < 0.05). After the second (left) sympathicotomy was done, the ST of both feet decreased (right, - 1.24 +/- 0.81oC and left, - 1.31+/- 0.77oC, P < 0.05) and the ST of both hands increased (right, 3.34 +/- 2.40oC and left, 2.11+/- 1.91oC, P < 0.05). There were increases of the ST in both hands (right, 4.93 +/- 2.51oC and left, 4.63 +/- 2.19oC) and decreases of the ST in both feet (right, - 3.38 +/- 1.85oC and left, - 3.09 +/- 2.03oC, P < 0.05) in the PACU. CONCLUSIONS: There may be a cross-inhibitory effect by the post ganglionic neurons innervating the blood vessels of the all extremities. Sympathicotomy causes the relief of the cross-inhibitory effect and result in vasoconstriction and a decrease of ST of contralateral hand and both feet.