ObjectiveTo determine the frequency and type of p16 gene homozygous deletion and mutation with the progression of human gastric carcinogenesis.MethodsPCR （polymerase chain reaction），SSCP (single strand conformation polymorphism) and DNA sequencing were performed on 50 operative tissues, which included 7 early gastric cancer and 43 advanced gastric cancer. In this group there were 36 male and 14 female patients aged 35 to 68,which included 30 welldifferetiated adenocarcinoma and 20 poordifferentiated carcinoma; 19 patients with lymph node metastases.ResultsTotal mutation frequency of p16 gene was 8.00%(4/50), including 14.29%(1/7) of early cancer and 7.00%(3/43) of advanced cancer，there was no significant difference between early and advanced cancer （P＞0.05）. In addition, p16 gene mutation was not related to site，location，grade of tumor differentiation and lymph node metastases, respectively. Total deletion frequency of p16 gene was 16.00%(8/50), of which 18.60%(8/43) was detected in advanced cancer, but no cases in early cancers. There was a significant difference between early and advanced cancer （P＜0.05）, and frequency p16 gene homozygous deletion was related to grade of tumor differentiation and lymph node metastases, respectively. Direct DNA sequencing displayed that 4 point mutations detected in 99,125,433,441 base, there were 3 missense mutation and 1 samesense mutation, no deletion or insertion was found. Conclusionp16 gene mutation is an early event in gastric carcinogenesis，it helps early diagnosis of human gastric carcinoma. p16 gene homozygous deletion is a late event in gastric carcinogenesis，it might relate to metastases and recurrence of gastric cancer.