Objective To examine loss of heterozygosity (LOH) and microsatellite instability (MSI) of locus D8S277 on chromosome 8 and their influence on the expression of PINX1 in the gastric carcinoma,which may provide an experimental basis for the mechanism of PINX1 gene and tumor development. Methods DNA was extracted from formalinfixed paraffinembedded tissues. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and ordinary silver staining were used to study LOH and MSI of locus D8S277. Envision immunohistochemistry and LeicaQwin computer imaging techniques were used to assess the expression of PINX1. Results The frequency of LOH was significantly higher in the cases with lymph node metastasis than in those without metastasis (21.15% vs 0, P<0.05),and was significantly higher in the cases at TNM stage Ⅲ＋Ⅳ than in those at stage Ⅰ＋Ⅱ(24.39% vs 3.33%, P<0.05). The positive rate of PINX1 protein was significantly higher in the cases without lymph node metastasis than in those with lymph node metastasis(78.95% vs 48.08%, P<0.05);and was significantly higher in the cases at TNM stage Ⅰ＋Ⅱ than those at stage Ⅲ＋Ⅳ(73.33% vs 43.90%, P<