MICB is a member of the MIC (MHC class I chain-related gene) family. Sixteen MICB alleles have been described; however, the functional relevance and population distribution of MICB alleles or their potential association to disease has not yet been evaluated. In this study, we have developed a PCR system using sequence-specific primers (PCR-SSP) that allows unambiguous amplification of all MICB alleles. This approach has been applied to type 100 healthy unrelated individuals from the Spanish population. The extent of polymorphism in this population is lower than that initially expected, and only nine alleles were detected. The alleles MICB01021 (46%), MICB0103101 (13.5%), MICB0104 (13.5%) and MICB0106 (12.5%) were found to be the most frequent alleles. HLA-B and MICA transmembrane polymorphism typing were also performed in this population. Our data showed that MICB is in linkage disequilibrium with MICA and even with HLA-B. Thus, the linkage disequilibrium with MICA and HLA-B suggests that MICB is a potential candidate for those diseases classically associated with HLA class I alleles.