OBJECTIVES: Anti-epidermal growth factor receptor (EGFR) therapies are ineffective in tumors with KRAS mutations in exon 2 codons 12 and 13. Thus, guidelines have recommended determination of KRAS mutation status in metastatic colorectal cancer (mCRC).  Both the cobas® KRAS Mutation Test (cobas® test, currently available as Research Use Only in the US) and the therascreen KRAS RGQ PCR Kit (therascreen test) detect KRAS mutations in exon 2; cobas® test detects twelve mutations and therascreen test detects seven mutations in exon 2. We estimated the potential clinical and budgetary impact of using the cobas® test versus therascreen test in the mCRC setting. METHODS: A budget impact model comparing the clinical and economic outcomes of using the cobas® test versus therascreen test was developed from the US payer perspective. We assumed 42,000 annual cases of mCRC patients. Model inputs were obtained from literature, whereas testing and treatment costs were calculated from CMS reimbursement rates. KRAS test sensitivity reflected the test’s ability to detect mutations in codons 12 and 13; specificity was assumed to be the same for both tests. The model calculated the average cost for mCRC patients over 5 years, using median time on treatment and median overall survival. Based on current practice patterns, the proportion of patients receiving KRAS testing before 1^st-line, 2^nd-line, and 3^rd-line therapy were 42%, 32%, and 26%, respectively. RESULTS: Adopting the cobas® test resulted in a reduction of 289 patient-months lost due to non-optimal care (i.e. by avoiding anti-EGFR therapies in mutant positive patients) and an improvement in median overall survival.  Adopting the cobas® test generated a total of $2.3 million in cost savings and an average decrease of $7 per mCRC patient per month. CONCLUSIONS: Using the cobas® test with improved sensitivity was associated with a reduction of patient-month lost and a decrease of healthcare costs in mCRC patients.