Objective: The aim of this study was to investigate the feasibility of sentinel lymph node biopsy (SLNB) in colorectal cancer. Methods: Twenty patients of colorectal cancer were enrolled in this study. Endoscopic injection submuco-sally of 99mTc-DX was performed around the primary tumor 3 h before operation. Immediately after laparotomy, methylene blue was injected into subserosal layer adjacent to the tumor. Sentinel lymph nodes (SLNs) were defined as blue stained nodes or (and) those containing 10 times more radioactivity than surrounding tissue with a γ probe, all resected nodes were examined postoperatively by routine rapid frozen examination and HE stain. The diagnostic nodes metastasis states and false-negative rate of regional lymph node status on the basis of SLNs were calculated respectively. Results: SLNs were detected in 16 of 20 patients with a successful detection rate of 80%, the number of SLNs ranged from 1 to 3, with a mean value of 2.4 per case, metastasis rate of SLNs were 37.5% (18/48), the diagnostic sensitivity was 80% (16/20), the diagnostic accuracy was 83.3% (15/18), the false-negative rate was 20% (4/20). Conclusion: The SLN concept is validated in colorectal cancer. Com-bined-agent SLN mapping is an accurate diagnostic procedure for detecting lymph node metastasis in patients with colorectal cancer and may indicate rational extent of lymphadenectomy for celorectal cancer.