RAS genotyping is mandatory for the prescription of anti-EGFR (epidermal growth factor receptor) therapies in patients with metastatic colorectal cancer. The standard genotyping is assessed on formalin-fixed paraffin embedded tumour tissue. This study compares RAS and BRAF genotyping results achieved in analyzing circulating plasma DNA using OncoBEAM™ technique with those achieved using the standard genotyping techniques and formalin-fixed paraffin embedded samples.