Abstract: Background: Dalbergia paniculata Roxb. (Fabaceae) is a tree that is widely distributed throughout Sourthern and Central India. It is known to possess antimicrobial, antioxidant, anti-inflammatory and antidiarrhoeal activities. No scientific evidence is available for the biological effects of this plant. This study aimed to isolate the isoflavonoids in the stem bark and leaves of D. paniculata and evaluates the antioxidant activity of the hydro-alcoholic extract and isolated compounds. Results and Conclusion: Four isoflavonoids were isolated from the chloroform-soluble part of the defatted ethanolic extract of the stem bark and leaves of D. paniculata. The structures of the isolated compounds were elucidated by chromatographic and spectroscopic means. The compounds were identified as biochanin A (1), genistein (2), dalpatein (3) and formononetin (4). Total flavonoid content was determined in the leaves (1.51±0.05), stem bark (0.83±0.08) and seeds (0.68±0.03). An RP-HPLC method using an isocratic conditions has been developed for analysis of the isolated isoflavonoids in different parts of D. paniculata. The alcoholic extracts of the leaves and stem bark as well as the isolated isoflavonoids exhibited significant in vitro antioxidant activities in 1, 1-Diphenyl-2-Picryl Hydrazyl (DPPH) radical scavenging assay. In vivo antioxidant activities of leaves, stem bark extracts and biochanin A were evaluated in alloxan-induced diabetic rats. There was a significant increase in blood glutathione level induced by leaves extract at the tested dose (100 mg kg-1 body weight).