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.