目的研究胃癌组织中ｐ５３和Ｃｍｙｃ的表达与多药耐药性（ＭＤＲ）的关系．方法应用ＬＳＡＢ免疫组织化学方法研究６７例（男４１例，女２６例，平均年龄４６±１５８岁）胃癌标本中ｐ５３，Ｃｍｙｃ和Ｐｇｐ的表达．结果本组胃癌中ｐ５３阳性３２例（４７８％），Ｃｍｙｃ阳性３７例（５５２％），Ｐｇｐ阳性３９例（５８２％）．淋巴结转移阳性胃癌ｐ５３阳性率（５６９％）和Ｃｍｙｃ阳性率（６４７％）显著高于淋巴结转移阴性的胃癌（Ｐ＜００５）．ｐ５３的异常表达与ｍｄｒ１基因表达呈显著正相关（ｒ＝０６３，Ｐ＜００５），而Ｃｍｙｃ和ｍｄｒ１的表达无明显相关．结论ｐ５３异常表达可增加ｍｄｒ１基因的表达，从而使胃癌细胞获得ＭＤＲ表型 Objective To study the relationship between the expression of p53 and Cmyc and multidrug resistance (MDR) in gastric cancer. Methods The expressions of p53, Cmyc and Pgp in gastric cancer specimens of 67 patients (41 males and 26 females, mean age 46±158 years) were studied by LSAB immunohistochemistry. RESULTS: In this group, 32 cases (47.8%) of p53 were positive, 37 cases (55. 2%) were C-myc positive, and 39 cases (58. 2%) were P-gp positive. The positive rates of p53 (56.9%) and C-myc (64.7%) in gastric cancer with lymph node metastasis were significantly higher than those with negative lymph node metastasis (P<0. 05). The abnormal expression of p53 was positively correlated with the expression of mdr1 gene (r=063, P<005), but the expression of Cmyc and mdr1 was not significantly correlated. Conclusions The abnormal expression of p53 can increase the expression of mdr1 gene, so that gastric cancer cells can obtain the MDR phenotype.