Considering the wide divergence in the frequency of KRAS and BRAF mutations in the precursor lesions of CRC and the absence of data in the Chinese population, the aims of this study are to investigate the frequency of KRAS and BRAF mutations in precursor lesions of colorectal cancer in a Chinese population and to study the association between molecular alterations and histologic features. The gene discussed is KRAS; the disease is colorectal cancer.