【Abstract】ObjectiveTo detect the spreading scope of rectal cancer to mesorectum by RT-PCR using carcinoembryonic antigen (CEA) mRNA as a marker and to investigate the excision scope of mesorectum in resection of rectal cancer. MethodsForty specimens from 40 rectal cancer patients who underwent curative operation was employed to detect the metastatic deposits scattered in the mesorectum by RT-PCR using CEA as a marker. ResultsNine of 40 (22.5%) specimens contained metastatic deposits scattered in the mesorectum. The metastasis was just within the range of 4cm mesorectum under the verge of tumor. The tumor spreading to mesorectum is correlated with Dukes stages，the infiltrated depth of bowel wall, tumor differentiation and tumor type(P＜0.05), and is not correlated with the size of tumor and the level of CEA(Pgt;0.05). ConclusionThe excision of mesorectum should be within the range of 5cm under the verge of tumor in surgical management of rectal cancer.