Terminalia arjuna (Arjuna), belonging to family combretaceae, grows along the streams or rivers and often in the shallow streambeds and riverbeds in central India. It has been considered by the Ayurvedic physicians as well as by the modern practitioners as a cardiac tonic. Clinical evaluation indicated that it has been found beneficial in the treatment of coronary artery disease, heart failure, and possibly hypercholesterolemia. It has also been found to possess antibacterial, antimutagenic and antioxidant activities. Demand for T. arjuna bark, both in India and abroad has been increasing rapidly for over a decade. About 95 percent of the requirement is met from the wild and collected in a pattern that is not concomitant with sustainable harvesting practices. The quality of the bark is directly dependent on harvesting technique and time. There is also a clear relationship between the part of the plant harvested, harvesting method used, and the impact of these on the plant. Keeping above into consideration it has been planned to carry out systematic study on phytochemical investigation of Arjuna bark collected from various parts of the tree at different harvesting time. The bark samples were analyzed for tannin and oxalic acid. The tannin and oxalic acid content varied from 6.75 to 14.82 % and 7.66 to 20.05 % respectively in various samples of T. arjuna bark collected from various places of Madhya Pradesh. The middle-aged trees having GBH around 130 cm were found to contain more amount of tannin. The study gives important information to obtain better quality of T. arjuna bark on sustainable basis.