The Centers for Medicare & Medicaid Services and Centers for Disease Control and Prevention published a final rule that would update 1992 proficiency testing and referral requirements under the Clinical Laboratory Improvement Amendments. Nearly 36,000 CLIA-certified laboratories, including hospital laboratories, are enrolled in CMS-approved proficiency testing programs. The final rule addresses and updates current analytes (that is, substances or constituents for which the laboratory conducts testing) and newer technologies. It also finalizes regulations to reflect those laboratories that perform moderate- and high-complexity testing and voluntarily participate in proficiency testing for waived tests (for example, simple tests, such as urine pregnancy tests) are subject to compliance. In the final rule, and a related Fact Sheet, CMS states that this will align the regulations with the CLIA statute, which does not exclude waived tests from the ban on improper proficiency testing referral.