We have developed a highly accurate, low-cost, single-step, mutagenically separated polymerase chain reaction (MS-PCR) method for the determination of angiotensin II type-1 receptor (AT(1)) A1166C gene polymorphism. The genotypes are determined using the microtiter array diagonal gel electrophoresis (MADGE) system. We have compared the MS-PCR method with allele-specific oligonucleotide hybridization and Dde I digestion techniques for determining the AT(1) A1166C genotype. The combination of MS-PCR and MADGE serves as a model for high-throughput single-nucleotide polymorphism genotyping in large population studies.