OBJECTIVES: The US Food and Drug Administration's Final Rule on laboratory-developed tests was published on May 6, 2024. The objective of this article is to explain the Final Rule and existing in vitro diagnostic regulations in the context of anatomic pathology. METHODS: The Final Rule, US in vitro diagnostic regulations, guidance documents, government publications, websites, news articles, and publications were reviewed, with sources including the Federal Register, the Code of Federal Regulations, the US Code, statutory text, PubMed, and Internet resources. Regulations applicable to device classifications and product codes relevant to anatomic pathology were highlighted. RESULTS: The Final Rule outlines requirements and enforcement discretion policies applicable to anatomic pathology, including the Food and Drug Administration's targeted enforcement discretion for "1976-type" laboratory-developed tests and partial enforcement discretion with laboratory-developed tests for unmet needs. Existing regulations, including the classification and requirements applicable to Class I, II, and III medical devices, are reviewed, including those for immunohistochemistry kits and reagents, analyte specific reagents, and research use only reagents and equipment. CONCLUSIONS: Pathologists, laboratory directors, managers, and supervisors responsible for anatomic pathology testing should be familiar with existing regulations and the Final Rule to ensure compliance with federal laws and regulations.