Fennel fruit consists of the dried ripe fruit of Foeniculum vulgare Mill. (Fam. Apiaceae); it has been used in traditional medicines for a wide range of ailments related to digestive, endocrine, reproductive, and respiratory systems. The marketed fennel fruit is sometimes adulterated with fruits of Carum carvi L., Cuminum cyminum L. and Anethum graveolens L. or is much lower quality due to unsuitable processing and storage. USP is developing Fennel Fruit quality standards to help protect customers from using incorrect and low-quality fennel fruit. The USP Fennel Fruit monographs provide analytical quality control procedures and acceptance criteria with suitable reference standards. The monograph contains identification methods utilizing GC, HPTLC and botanical characteristics, and a GC assay method. Both GC and HPTLC identification methods in the monograph can detect anethole, a major component of fennel fruit. The three potential confounders do not contain anethole, which can efficiently differentiate the fennel fruit from the potential confounders. The GC assay can quantify content of anethole, limonene, fenchone, and estragole concurrently. Test results indicated the content ratio of anethole to fenchone in fennel fruit is much different from bitter fennel (Foeniculum vulgare Mill. var. vulgare) fruit a variety of fennel used in Europe. The USP Laboratory tested some commercial fennel products using the monograph methods and found that some of the products did not contain any related components in both GC and HPTLC chromatograms, implying that the fennel fruit maybe an exhausted product which may not be acceptable for use as a dietary ingredient.