We report on the potential of the photocurrent technique as analytical tool for diode laser testing. The physics involved into the generation of photocurrents as well as experimental requirements for detecting them are highlighted. Based on a number of practical examples, we demonstrate how knowledge about the photoelectrical properties of diode lasers can help to learn about stress and defects within packaged devices or how non-perfect device fabrication may be discovered. These results are discussed in conjunction with device reliability issues.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.