Which Laboratories Can Test DOT Drug Specimens?

Only laboratories certified by the U.S. Department of Health and Human Services (HHS), or laboratories in Canada or Mexico that qualify under 49 CFR 40.81(b), can test DOT drug specimens. Under 49 CFR 40.81(a), a drug testing laboratory in the United States may take part in DOT drug testing only if HHS certifies it under the National Laboratory Certification Program (NLCP) for each specimen testing methodology it performs under Part 40. The specimen types allowed under Part 40 are covered in What Types of Drug Tests Are Allowed under DOT Rules?.

Under 40.81(b), a laboratory in Canada or Mexico that HHS has not certified may take part only in one of two ways. DOT, based on a written recommendation from HHS, may approve the laboratory as meeting HHS certification standards or as fully equivalent to such a laboratory. DOT may also, based on a written HHS recommendation, recognize a Canadian or Mexican certifying organization as having equivalent standards, and that organization then certifies the laboratory.

Under 40.81(c), a laboratory follows Part 40 and all applicable HHS requirements in testing DOT specimens, whether or not Part 40 states those HHS requirements. Under 40.81(d), a laboratory that DOT finds in noncompliance could face a public interest exclusion (PIE) under Subpart R of Part 40. A laboratory under a PIE cannot take part in DOT drug testing, even if it continues to meet the certification requirements.

HHS also certifies Instrumented Initial Testing Facilities (IITFs), which are listed separately from laboratories. The HHS list published in the Federal Register on September 30, 2026 notes that DOT does not allow IITFs to test DOT-regulated specimens.

Labs listings in the MyDrugTesting.com directory do not show HHS certification, so certification can be checked against the current HHS list.