Our data support the reported role of p21ras oncogenesis in progression along the adenoma to the carcinoma pathway (Fearon and Vogelstein, 1990), since the k-ras mutation frequency increased from 5.6% in mildly dysplastic adenomas to 23.3% in moderately dysplastic adenomas, the frequency of k-ras mutation increased with villous content and, the highest proportion of mutations was observed in adenomas greater than 10 mm in size. This evidence concerns the gene HRAS and adenoma.