OBJECTIVES: The use of K-ras testing in clinical decision-making has grown over the past few years. The objective of this study was to evaluate, in a real world context, the trends and diagnostic findings of K-ras testing using managed care and EMR data. METHODS: The Georgia Cancer Specialists Database EMR (2005-2010) and administrative data from the MarketScan and IMPACT database(s) was used to select patients with newly diagnosed colorectal cancer (CRC). We looked for trends in use of K-ras in relation to timing of chemotherapy administration. The EMR data provided information on k-ras mutation type. RESULTS: In MarketScan, of the 23,548 patients with a diagnosis of CRC, 1,730 (7.3%) patients had a test ordered for K-ras between 2005 and 2010. The number of patients receiving K-ras increased with line of therapy: first line 336 patients (8.2%) of 4098 treated, second line 455 patients (15.2%) of 2984 treated, and third line 529 patients (33%) of 1603 treated. We found similar results using the IMPACT database: 2,256 (7.8%) CRC patients had a test ordered for K-ras between 2005 and 2010.  K-ras testing increased with line of therapy: first line 244 patients (7.8%), second line 510 (14.6%), and third line 650 patients (33.1%). EMR lab results from stage IV disease (n=349) consisted of 15% mutated type, 60% unknown and 25% wild type. For confirmed test results wild type represented 62.5% and mutated type 37.5%. CONCLUSIONS: Over the last six years, use of K-ras testing has increased in use in patients with CRC. The increase has occurred in later lines of therapy. The timing occurring late in therapy may limit the use of agents specific for this test.