In this study, we investigated the killer cell immunoglobulin-like receptor (KIR) genes and HLA-C1/C2 dimorphism in 819 healthy, unrelated individuals composed of two southern Chinese Han populations (Hunan Han and Guangdong Han) and two northern Chinese populations (Inner Mongolia Han and Inner Mongolia Mongol), using polymerase chain reaction-sequence-specific priming (PCR-SSP) method. Fifty-one Chinese families were used to determine KIR haplotypic configuration. Our data showed that KIR2DL4, KIR3DL2, KIR3DL3, and KIR3DP1 genes were present in all of the 819 individuals. However, KIR2DL4 and KIR3DP1 genes were not detected in two members of a northern Chinese family. None of the KIR genes showed significant difference between the four populations. Thirty-five different KIR gene profiles were identified, one of which has not been previously reported in the Allele Frequencies KIR database. Eleven distinct KIR haplotypic configurations were determined through family analysis. Individuals with KIR2DLl and KIR2DL3 genes but lacking KIR2DSl and KIR2DS2 genes, coupled with HLA-C1 (Asn 80 ) homozygosity, predominated in each population. At least one known inhibitory KIR–HLA pair was detected in each individual. The findings shown here are valuable for future studies of the potential role of KIR genes as well as KIR–HLA interaction in disease susceptibility in related ethnic groups.