Pharmacognostical standardization of crude drugs is essential before carrying out its scientific validation as it furnishes the identity and authenticity of the plant. The present study is concerned with the macro-microscopical evaluation & DNA bar code screening of the leaves of Clinacanthus nutans (Burm.f.) Lindau. It is a perennial herb of the Acanthaceae family, widespread in Tamilnadu & Kerala and locally known as Visha pacchelai is a folk medicine. Macroscopic characteristics viz. size, shape, colour, odour and taste were determined. Microscopic evaluations were performed by using a high-resolution microscope. The anatomy of the leaves was examined by following the standard method of section cutting. Species identification using DNA barcoding was done based on the pattern of nucleotide arrangement in a fragment of DNA of a particular species and its maximum percentage of identity. The macroscopic assessment showed that the plant leaves are dark green in colour, simple, opposite, narrowly elliptic-oblong or lanceolate having slightly characteristic odour with salt, astringent and sweet taste. Dorsiventral lamina, irregular polygonal cells, uniseriate epidermis-bearing trichomes, V-shaped petiole, horseshoe shape vascular bundles, thin xylem fibres, pitted tracheids, anisocytic stomata, unicellular warty, septate trichome were all revealed in detailed microscopy. DNA quantification by spectrophotometer showed an A260/280 ratio of 1.8, indicating the purity of DNA. The macro-microscopic findings and DNA barcode analysis of the Clinacanthus nutans (Burm.f.) Lindau leaf are applicable for standardization and authentication of the plant.