目的　扩增石蜡包埋小鼠组织 p5 3基因第 5、7外显子。方法　用 3种方法提取DNA ,比较提取效果 ,用聚合酶链式反应 (PCR)扩增相应片段。结果　用二甲苯脱蜡 ,蛋白酶K消化 12 0小时可获得较好的DNA提取物。结论　用该提取物为模板扩增小鼠p5 3基因突变热点片段成功率高 Objective To amplify exon 5 and exon 7 of p5 3 gene in paraffin-embedded mice. Methods Three kinds of methods were used to extract DNA. The extraction effect was compared. The corresponding fragments were amplified by polymerase chain reaction (PCR). The results dewaxing with xylene, proteinase K digestion 12 0 hours to obtain a better DNA extract. Conclusion The successful extraction of mouse p5 3 gene mutation hot spot fragment using this extract as a template has a high success rate