Next-generation sequencing (NGS) is currently used in the clinical setting for targeted therapies and diagnosis of hematologic malignancies. Accurate detection of somatic variants is challenging because of tumor purity, heterogeneity, and the complexity of genetic alterations, with various issues ranging from high detection design to test implementation. This article presents guidelines developed through consensus among a panel of experts from the Korean Society for Genetic Diagnostics. They are based on experiences with the validation processes of NGS-based somatic panels for hematologic malignancies, with reference to previous international recommendations. These guidelines describe basic parameters with emphasis on the design of a validation protocol for NGS-based somatic panels to be used in practice. In addition, they suggest thresholds of key metrics, including minimum coverage, mean coverage with uniformity index, and minimum variant allele frequency, for the initial diagnosis of hematologic malignancies.