Abstract: An endoscope warmer for preheating endoscopic surgical instruments, wherein the warmer comprises a holster, a plurality of channels formed in the wall of the holster for circulating a heated fluid, a supply port and a return port for maintaining a constant supply of heated fluid, and a pocket defined by the holster for receiving at least the optical shaft portion of the instrument and, in the alternative, the entire instrument. The supply and return ports are sealingly attached to the holster and are adaptable for connection to heating units and pumps for circulating the heated fluid through the holster.