Extraction has been the primary method of concentrating and obtaining a crude essence of plants, and to an extend fruits and nuts. In modern times, there are many methods of extraction developed from simple maceration to using Soxhlet extractor to microwave assisted extraction and ultrasound assisted extraction. However, the more time saving and energy efficient method for the extraction of plants needs to be investigated. This research explored optimization of ultrasound assisted extraction of flavonoids from Leucas zeylanica and the optimization was done on parameters of sonication time (minutes), water bath temperature (°C), volume of solvent to solid ratio (ml/g) and solvent concentration (%) using response surface methodology (RSM). By measuring the total flavonoid content using aluminium colorimetric method and UV visible spectrophotometry, highest flavonoid yield is achieved with 30.38% increase compared to unoptimized method. This occurred with sonication time of 42 minutes, temperature of 55°C, solvent to solid ratio of 40 ml/g and solvent concentration of 100%. The resulting extract was then tested for its anthelmintic (anti-worm) ability, obtaining 40% efficacy of that of Albendazole.