Introduction: Different parts of Pongamia pinnata (L.) Pierre shows valuable pharmacological activities. The flowers are used as major ingredient of Pongam poo choornnam, a siddha formulation used for reducing the constant rise of body temperature due to veneral diseases. This study is a detailed pharmacognostic evaluation of the macro and microscopic characteristics to authenticate P. pinnata flowers. Methods: The flowers were collected from Siddha medical college campus Arumbakkam and detailed pharmacognostic study employing morphological, anatomical, quantitative and powder microscopy was performed following standard procedures to assess authenticity of P. pinnata flowers. Result: The detailed microscopy of flower showed the presence of mesophyll cells and vascular bundles on the floral parts; quantitative microscopy revealed the dense distribution of trichomes on both surfaces of calyx and corolla, the epidermal number, trichome number, vein islet and vein termination number were also recorded; powder microscopy showed the presence of characters like epidermal cells, trichomes, parenchyma cells, vessels, fibres and pollen grains. Conclusion: This work will serve as an informative record of macro-microscopic features of this valuable floral drug.