637 Background: In mid-2013, the requirement for mCRC patients treated with panitumumab changed from wild-type KRAS to wild-type RAS ( KRAS and NRAS). The objective of this study was to describe patterns of KRAS, NRAS, and BRAF testing among mCRC patients in the EU5 (United Kingdom (U.K.), Germany, France, Italy and Spain). Methods: This descriptive study utilized Oncology Analyzer data (IMS Health Oncology, Fairfield, CT, USA), which provides real-world quarterly cross-sectional, epidemiologic and clinical data for mCRC patients. Trends in biomarker testing during the study period were evaluated by calculating the frequencies and proportions of patients who were /were not tested for combinations of KRAS, NRAS, and BRAF within each of the five countries. KRAS and BRAF data were available in all countries from quarter three (Q3) 2012 to quarter two (Q2) 2015. NRAS was available in all countries from quarter 1 (Q1) 2014 to Q2 2015. Frequencies and proportions were also calculated to summarize patient demographic and clinical characteristics between groups with different testing choices. Results: A total of 32,961 patients with mCRC were included in the analyses. Prior to 2013, the majority of patients in each country were tested for only KRAS. The proportion of patients tested for both KRAS and NRAS increased substantially during the period of data availability for NRAS (Q1 2014 to Q2 2015), including <1% to 19.1% in the U.K., 8.8% to 31.9% in France, 13.1% to 43.2% in Germany, 5.9% to 24.6% in Italy, and 8.7% to 31.4% in Spain. The proportion of patients who were tested for all three biomarkers also increased during the period of data availability for all three biomarkers (Q1 2014 to Q2 2015), including 2.3% to 16.4% in the U.K., 4.8% to 26.6% in France, <1% to 2.4% in Germany, 4.2% to 22.3% in Italy, and 1.5% to 9.3% in Spain. There were few differences in patient demographic or clinical characteristics between those with different testing groups. Conclusions: This analysis provides a description of biomarker testing using read-world data and suggests an overall increase in testing among mCRC patients in the EU5. Although there was a trend towards increased testing, many mCRC patients are still not tested for these important biomarkers.