To elucidate the molecular pathology underlying the deve lopment of hepatocellular carcinoma (HCC), we used 41 highly polymorphic microsatellite markers to examine 55 HCC and cor responding non-tumor liver tissues on chromosome 9, 16 and 17. Loss-of-heterozygosity (LOH) is observed with high fre quency on chromosomal region 17p13 (36/55, 65%), 9p21-p23(28/55, 51%), 16q21-q23 (27/55, 49%) in tumors. Meanwhile,microsatellite instability is rarely found in these microsatellite loci. Direct sequencing was performed to detect the tenta-tive mutation of tumor suppressor genes in these regions: p53,MTS1/p16, and CDH1/E-cadherin. Within exon 5-9 of p53gene, 14 out of 55 HCC specimens (24%) have somatic mutations, and nucleotide deletion of this gene is reported in HCC for the first time. Mutation in MTS1/p16 is found only in one tumor case. We do not find mutations in CDH1/E-cadherin.Furthermore, a statistically significant correlation is present between p53 gene mutation and loss of chromosome region 16q21q23 and 9p21-p23, which indicates that synergism between p53 inactivation and deletion of 16q21-q23 and 9p21-p23 may play a role in the pathogenesis of HCC.