Phytochemical and Pharmacognostic Investigation on Oldenlandia corymbosa (L.) Lamk. Of Rubiaceae, has been undertaken. The present investigation involves the macroscopy, microscopy, which showed Prismatic crystals in the transverse section of leaf and stem. Both the surfaces of leaf showed the paracytic type of stomata and the number of stomata were more on the lower surface. Preliminary phytochemical analysis revealed the presence of amino acids, gums, steroids, alkaloids, tannins and phenolic compounds. Microscopic investigations on crude drug powder showed the presence of spiral, pitted, and annular vessels, phloem elements, tannin cells and Prismatic crystals.