A single-stage flash-lamp-pumped waveguide dye laser amplifier is presented. A Pyrex cylindrical dye cell filled with a rhodamine 6G solution in ethanol acts as an active hollow dielectric waveguide for the light to be amplified. Over-all efficiency and absolute energy gain are about one order of magnitude larger than for a conventional single-pass dye laser amplifier. Such a device can be conveniently used when inserted, with suitable couplers, in an optical waveguide system.