Laboratories are increasingly required to perform molecular tests for the detection of mutations in the KRAS gene in metastatic colorectal cancers to allow better clinical management and more effective treatment for these patients. KRAS mutation status predicts a patient's likely response to the monoclonal antibody cetuximab. To provide a high standard of service, these laboratories require external quality assessment (EQA) to monitor the level of laboratory output and measure the performance of the laboratory against other service providers. National External Quality Assurance Services for Molecular Genetics provided a pilot EQA scheme for KRAS molecular analysis in metastatic colorectal cancers during 2009. Very few genotyping errors were reported by participating laboratories; however, the reporting nomenclature of the genotyping results varied considerably between laboratories. The pilot EQA scheme highlighted the need for continuing EQA in this field which will assess the laboratories' ability not only to obtain accurate, reliable results but also to interpret them safely and correctly ensuring that the referring clinician has the correct information to make the best clinical therapeutic decision for their patient.