Abstract: A system and method are provided for thermally treating tissues in percutaneous surgery or endoluminal treatments. The system consists of at least one catheter for thermally treating a tissue, hydraulic unit for circulating fluids through the catheters and a control station by which an operator is displayed with, and inputs and/or modifies, working parameters of the system. The catheters have an operational face, which is optionally expandable and encloses a lumen through which the fluids are circulated. The method disclosed implements cooling of the targeted tissue prior to its heating. For heating and or cooling the tissues, the operational face of a catheter is pressed against a surface of the targeted tissue while heat emitted from or conducted to the tissue is respectively transferred into or from the circulated fluids.