To realize a completely monolithic, pulsed, fiber laser without free space elements we describe a gain-switched fiber laser pumped with a pulsed diode laser at about 965 nm with more than 30 μJ in a 200 ns pulse. For best beam quality we use a single mode fiber with a 6 μm core diameter. We report lasing of an Yb-doped double-clad fiber at 1080 nm and a pulse energy of about 8 μJ with a variable repetition rate from 1 - 50 kHz. The experimental results are compared with the data of a time resolved simulation and basic analytically derived formulas.© (2009) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.