Forward genetic screens have been a powerful tool for discovering genes involved in various biological processes in Caenorhabditis elegans. Here, we present a protocol for forward genetic screening to identify novel factors involved in a biological process in C.elegans. We describe steps for mutagenesis, screening, and backcrossing. To save time and effort, we also detail procedures for utilizing whole-genome sequencing to exclude mutants of previously characterized genes from crosses for mapping mutations. For complete details on the use and execution of this protocol, please refer to Yoshida et&#
xa0;al.<sup>1</sup>.