A laser energy delivery device and method are provided for irradiating a body tissue with relatively long wavelength laser energy in the presence of an aqueous liquid without significant absorption of the laser energy by the liquid. The device includes an elongate hollow sheath that is open at its distal end and closed at its proximal end, a laser energy conduit such as an optical fiber or hollow waveguide, within the sheath, the distal end of the conduit being disposed near the open distal end of the sheath, and the proximal end of the conduit being adapted for connection to a source of long wavelength laser energy. The sheath also includes an inlet port, spaced from the proximal end of the sheath, and adapted to receive and deliver a biologically compatible gas through the sheath to a body tissue site in contact with the open distal end of the sheath.