The genus Cinnamomum belongs to the family Lauraceae, which is found and diverse in tropical and subtropical regions, comprising approximately 55 genera with 3000 species. Among the economically important Laurales, the genus Cinnamomum is significant not only for its economic value but also for its health benefits. This chapter discusses the use of anatomical characteristics (macro- and micro-morphology, petiole, leaf, stem, and root) and molecular techniques (developed before and after the advent of polymerase chain reaction (PCR) technology) for genetic diversity studies in Cinnamomum species from Sri Lanka. Although there are eight Cinnamomum species in Sri Lanka, C. zeylanicum is the most economically important species and is used for multiple purposes. In the farmer’s field, a variation is found based on morphological characters. Therefore, accurate species identification and complete and comprehensive studies of the genus are essential for conservation and breeding purposes. Although very few anatomical studies have been conducted on the Cinnamomum species found in Sri Lanka, this chapter explains the anatomical variation using light microscopy and scanning electron microscopy among the Cinnamomum species. This chapter aims to fill the data gap on the anatomical characters of the leaf, petiole, stem, and root and molecular markers of Cinnamomum species. Cuticular sculptures and cuticular features could serve as excellent diagnostic criteria in the delimitation of Cinnamomum species. The distinguishing characters of taxonomic value include the variation in shape of the petioles, arrangement and shape of petiole vascular bundles, presence/absence of hairs, hair types, distribution of hairs on the petiole, type and distribution of crystals, pigments and sclerides, wood anatomical features, including the presence and types of trichomes, crystals, sclereids, and vessel arrangements, which are valuable in delimiting and identifying Cinnamomum species. In all species, the barks were characterized by different colored (dark golden brown, dark red, or dark brown) pigments, the presence of islands of sclerenchyma in the pericycle, mucilage or oil droplets in the cortex, radially arranged vascular system consisted of diffuse-porous or semi-ring porous in wood, growth ring boundaries distinct or intermediate between distinct and indistinct, and solitary vessels in radial or diagonal multiples of 2–3 cell. Vessels of most species were evenly distributed, round to oval, with simple or scalariform perforation, bordered and alternate inter-vessel pitting, with tyloses, vasicentric axial parenchyma, uniseriate rays, and multiseriate rays. Moreover, allozyme variation and DNA-based markers, including randomly amplified polymorphic DNA, SRAP (sequencerelated amplified polymorphism), PCR-AFLP (PCR-restriction fragment length polymorphism), ISSR (inter-simple sequence repeat), and chloroplast barcoding of the matK, rbcL, rpoB, rpoC1, ITS of trnH-psbA, trnL-F, atpF-atpH, and psbK-psbI have been employed in the identification and diversity studies of Cinnamomum species. Moreover, the DNA variation of the Cinnamomum species found in Sri Lanka and other Laurales found in the world has been discussed.