p53 gene in human esophageal cancer (EC) and cancer of gastric cardia was analyzed. Southern blotting hybridization revealed that five of 35 of EC sample were found to contain abnormal structure of p53 gene, including 2 deletions and 3 rearrangements; two of 27 adjacent non-tumor tissues also contain abnormal structure of p53 gene (7.4%), among them one case was fragment deletion and another case was rearrangement. PCR-direct sequencing technique was used to detect p53 point mutation within exon and intron 5 through 9. Fifteen of 30(50%) of esophageal squamous cell carcinomas contained mutation of p53 gene. Five of 11(45%) adjacent non-tumor tissues also contained mutation of p53 gene. An esophageal adenocarcinoma showed p53 mutation. Three of 4 carcinoma of gastric cardia showed p53 mutation. Mutation spectrum in EC: 8 of 22 cases (36.4%) of p53 mutation were G:C to A: T transition, 6 of 22 cases (27.3%) of p53 mutation were frameshift mutation, including 13.6% (3/22) insertion and 9.1% (2/22) deletion mutation. Some new sites of p53 mutation in human EC were identified. The results suggest that the p53 gene plays an important role in carcinogenesis of human esophagus and gastric cardia.