Numerous genomic tests are available for use in colorectal cancer, with a widely variable evidence base for their effectiveness and cost-effectiveness. In this review, we highlight many of these tests, with a focus on their proposed role, the evidence base to support that role, and the associated costs and risks. The tests with the strongest evidence base are KRAS genetic testing in the metastatic setting and microsatellite instability testing in selected patients and in stage II disease. There also may be a role for delineating recurrence-risk signatures for selected patients with stage II disease. The evidence to support broad utilization of uridine 5'-diphospho-glucuronosyltransferase 1A1 (UGT1A1) and dihydropyrimidine dehydrogenase (DPD) testing to guide irinotecan and fluorouracil dosing remains limited. There is much anticipation that next-generation sequencing will herald a new era of targeted therapy for patients with colorectal cancer; however, currently there are no data to support the introduction of widespread testing.