Anatomical and histochemical studies on leaves of Syzygium aromaticum and Clausena excavata have been carried out. This study was conducted in order to investigate the relationship between aroma production and a plant's secretory structures. Leaves from the two tropical aromatic plants were sampled from the Institute of Bioscience (IBS) Conservatory Park and transversely sectioned through lamina, midrib and petiole with a sliding microtome for anatomical investigation. Through light microscopy, oil cells and secretory cavities were distributed near the adaxial and abaxial epidermal layers with large in size, up to 60 µm length. Other leaf anatomical characters such as shape of petiole and midrib, pattern of vascular bundle, palisade and spongy mesophyll, the presence or absence of brachysclereids and crystals are also observed. This study also aimed to investigate the leaf's secretory structures responsible for plants' aroma production and to detect the presence of terpenes and essential oil in secretory structures histochemically.