Molecular genetic approaches for colorectal cancer screening using stool samples have the potential to be very specific, sensitive and cost effective. K-ras oncogene mutation, observed in about 50% of the colorectal tumours, serves as an ideal target for such an approach. Several studies have shown that K-ras gene mutations present in the tumours can be detected from the stool of patients with colorectal cancer. The challenge for clinical application, however, is to develop a simple method for robust PCR amplification and a reliable assay for K-ras gene mutation detection in the stool samples.