Department of Chemical Engineering, National Institute of Technology Tiruchirappalli, Tiruchirappalli, Tamilnadu - 620015, India. E-mail: ssankar@nitt.edu Manuscript received online 10 July 2020, revised and accepted 31 October 2020 This study was designed to improve phenolic yield using ultrasound assisted extraction from leaves of Polyalthia longifolia used for medicinal applications. The extraction of polyphenols was performed using probe type and bath type ultrasound sources to obtain maximum efficiency by optimizing the condition of extraction process like, type of solvent, powdered leaf to solvent ratio, extraction time etc. The results have showed better yield for an extraction time of 60 minutes using ultrasound bath with 50% methanol solvent and 1:25 powdered leaf to solvent ratio. Ultrasound assisted extraction yielded total polyphenols of 2756.86 (probe type) and 2954.36 (bath type) mg GAE/100 g of dry leaves whereas, in conventional method it was 2021.31 mg GAE/ 100 g of dry leaves. Also, the DPPH, FRAP and ABTS radical scavenging activity was measured to be 92.63, 86.99 and 92.18 % (probe type) and 95.76, 88.98 and 95.76% (bath type) from the optimized samples. Total flavonoid content obtained was 260.52 (bath type) and 189.66 (probe type) mg/100g of dry leaves. Therefore, it could be concluded that ultrasound assisted extraction process using methanol solvent showed highest polyphenolic yield and maximum antioxidant capacity when compared to conventional extraction process.