Recently a tumor suppressor gene, a deleted in malignant brain tumor gene (DMBT1), was detected on chromosome 10. In some types of tumors, the frequent deletion of DMBT1 locus have been reported as well as loss of heterozygosity (LOH) on chromosome 10. However, little is known relating to human oral squamous cell carcinoma (OSCC). To study the genetic aberrations on chromosome 10 in OSCC, we performed polymerase chain reaction (PCR) analysis of microsatellite polymorphisms corresponding to 16 loci, containing 2 DMBT1 loci. We examined 38 oral primary squamous cell carcinoma (SCC) tissues and corresponding normal tissues. Microsatellite instability (MI) was detected at least on 1 of the 16 loci in 15 (39.5%) of 38 cases, and loss of heterozygosity (LOH) at least 1 of the 16 loci was also observed in 28 (73.7%) of 38 cases. LOH was accumulated at D10S202 (34.6%) and D10S217 (28.6%), suggesting the presence of two putative tumor suppressor genes associated with OSCC. The 2 DMBT1 loci, D10S209 and D10S587, had comparatively high frequent LOH (20.0 and 22.7%, respectively), maybe indicating the important role of DMBT1 in OSCC. No significant correlation between histological differentiation and LOH was found. These results suggest that genetic aberrations on chromosome 10 play important roles in the oncogenesis of OSCC.