Senna splendida (Vogel) H.S.Irwin & Barneby (Leguminosae) is a ethnomedicinal species native to Brazil, popularly known in the country as “fedegoso-grande and “feijão-brabo”, it is used against kidney diseases, bronchitis, rheumatism, anemia and inflammations. A pharmacobotanical study of the aerial vegetative organs of S. splendida was carried out, looking for morphoanatomical data that can contribute to the taxonomy and quality control of its ethno-drugs. Paradermic sections of both epidermal surfaces and cross sections of the leaf and stem were made freehand. Histochemical tests were also performed to indicate the types of plant metabolites. Senna splendida is a sub-shrubby to shrubby, with cylindrical stems, leaves with 4-leaflets, sub-cylindrical petiole, leaflet blade are oblong or narrowly ovate, and carthaceous. In transverse section, the stem has the vascular system syphonostelic, ectophloic, continuous, consisting of a single circular vascular bundle, and a well-developed medullary parenchyma. The vascular system is collateral in the rachis, petiole, and midrib; the petiole and midrib showed four main bundles and two accessories; and the leaf rachis showed a main bundle and two accessories. The leaflet epidermis is hypostomatic, which has sinuous anticlinical cell walls on the both surfaces with anisocytic and paracytic stomata. The mesophyll is dorsi-ventral with a single-palisade, and 4-5-seriate spongy parenchyma. Inorganic idioblasts druse-type and prismatic crystals were observed near de vascular system of rachis, leaflet midrib, and petiole. Histochemical tests indicated the presence of starch, structural and non-structural phenolic compounds, alkaloids, and proteins in various parts of the leaflets, and also in the stem. The pharmacobotanical study of Senna splendida provided subsidies for its taxonomy and, in addition, it contributed to the quality control of its ethno-drugs and, thus, expanded the anatomical knowledge for the genus Senna. Financial support: CNPq and CAPES.