In order to evaluate the effects of ultrasound intensity (20-30, 40 kHz) and ultrasound exposure time (2-4-6 and 8 minutes) on germination, physiological and morphological characteristics of sesame, two separate experiments were performed in laboratory and research greenhouse of Shahrood University of Technology. The trials arranged in a factorial experiment based on a randomized complete block design with four replications. In the first experiment, germination percentage, the speed of germination, mean germination time, mean day germination, seed vigor index, root and shoot length, the coefficient of uniformity of germination, abnormal seedling percentage and some physiological characteristics including the activity of catalase and superoxide dismutase enzymes were evaluated. In the second experiment, emergence percentage, speed of emergence and morphological characteristics including plant height, leaf number and leaf area, root length, root to shoot ratio and total biomass were measured. Based on results, ultrasound exposure time had significant effects on all studied characteristics in both experiments, so that the highest and lowest mean value was related to the 8 and 2 minute respectively. Ultrasound intensity significantly influenced most of the studied characteristics and the highest and lowest mean was obtained at 40 and 20 kHz respectively. The interaction of ultrasound intensity and ultrasound exposure time were significant on most of traits. According to the results, it can be concluded that the use of ultrasound irradiation could greatly improve the germination, morphological and physiological characteristics of sesame.