This study aimed to characterize the morphological and anatomical diagnostic features of Epilobium angustifolium L. raw material, a widely distributed species in the Azerbaijani flora, to establish identification criteria for quality control purposes. Plant material was collected during the flowering stage in August 2021 from Malham village, Shamakhi district, Azerbaijan. The investigation utilized the entire herb, including both aerial (stem, leaves, flowers) and subterranean (root) parts. Anatomical examination was performed using light microscopy on semi-thin sections prepared from specimens processed with standard histological fixation and embedding techniques. The anatomical study revealed several distinctive diagnostic characteristics: the leaves exhibit a dorsoventral structure with an astomatous upper epidermis; the lower epidermis contains anomocytic stomatal complexes; the floral pedicel and the base of the calyx are densely covered with non-glandular trichomes; and the sepals are pigmented, with a lilac-colored, glabrous basal interior. The identified morphological and anatomical features represent reliable taxonomic and pharmacognostic markers for authenticating E. angustifolium raw material. These characteristics will support the standardization and quality control of herbal preparations and provide a foundational reference for compiling a comprehensive Pharmacopoeia monograph for this medicinal plant.