A high-throughput genotyping method has been developed to detect gene deletion polymorphisms of glutathione-S-transferase theta and mu (GSTT1 and GSTM1). This method utilizes the 5'-nuclease activity of Taq polymerase in conjunction with fluorogenic TaqMan probes. In contrast to traditional allelic discrimination genotyping to detect single nucleotide polymorphisms, the current assay has been designed to detect gene deletion by utilizing custom-designed TaqMan probes in conjunction with an exogenous internal positive control probe. The TaqMan genotyping results were validated by a commonly used multiplex PCR technique. Screening of 71 unrelated individuals revealed gene deletion (null) genotype of 15.5% and 40.8% for GSTT1 and GSTM1, respectively. This TaqMan genotyping method is rapid, reproducible, and highly sensitive and could be applied toward fully automated large-scale genotyping.