Short answer: Medicare Part B covers medically necessary diagnostic blood tests ordered by a doctor or other qualified health care provider. Medicare also covers specified preventive blood tests and screenings when the patient meets the applicable requirements.
Original Medicare coverage
Covered diagnostic laboratory tests can include blood tests, urinalysis, and tests on tissue specimens. The test must be used to diagnose, monitor, or rule out a medical condition and must be ordered by a qualified provider. Medicare also covers certain preventive laboratory services, such as cardiovascular, diabetes, hepatitis, and other screenings, according to separate eligibility and frequency rules.
Eligibility and limits
The test must be reasonable and medically necessary or must meet the requirements of a covered preventive benefit. Medicare may deny a test that is performed more often than the coverage rule allows, lacks a covered diagnosis, or is not ordered properly. A panel may contain tests with different coverage rules.
Where the specimen is collected and how the laboratory bills the service can affect the claim. The laboratory must be eligible to bill Medicare. Services associated with the test, such as a doctor visit or hospital outpatient charge, are billed separately.
Costs
You usually pay nothing for a Medicare-covered diagnostic laboratory test. Covered preventive laboratory tests are also commonly provided without cost when all requirements are met and the provider accepts assignment. A separate office visit, specimen collection service, or hospital outpatient service may have a deductible, coinsurance, or copayment.
Medicare Advantage
Medicare Advantage plans cover Medicare-covered laboratory services. A plan may require the use of an in-network laboratory or impose referral or authorization rules. Using an out-of-network laboratory may increase costs except where plan rules or emergency protections apply.
What to do next
- Ask which tests were ordered and which diagnosis supports them.
- Confirm that the laboratory accepts Medicare or is in your plan’s network.
- Ask whether the visit or specimen collection has a separate charge.
- Review your Medicare Summary Notice or plan explanation of benefits after testing.
Coverage is determined from the claim, the patient’s eligibility, provider status, and applicable Medicare rules. A provider’s recommendation does not guarantee payment. Before a planned service, ask the provider what will be billed and ask Medicare or the plan whether any coverage review is required.
Sources
Last reviewed: August 2026. Medicare rules and plan benefits can change.