Objective: The research aims to compare the effect of Tabata training (20 seconds work: 10 seconds rest) and modified Tabata training (10 seconds work: 5 seconds rest) on the development of some physical and physiological variables for taekwondo juniors under 17 years. Research procedures: The basic research sample was (14) players to whom the training program was applied for a period of 10 weeks, consisting of 2 training units. All players completed the following tests before and after the training program: physical tests, specific taekwondo aerobic endurance test, multiple kicking speed repetition test, and 20-meter multi-stage fitness test. The data were processed statistically using the following statistical methods: arithmetic mean, standard deviation, median, skewness coefficient, Mann-Whitney test, correlation coefficient, Wilcoxon test, and percentage improvement equation. Results: Tabata training and modified Tabata training had a positive effect on the development of some physical and physiological variables for taekwondo players under 17 years. There were statistically significant differences between the first experimental groups (Tabata training) and the second (modified Tabata training) in the post-measurement in some variables (specific agility, vertical muscular ability, Movement speed, and the variable of total kicks in 10 seconds in the special anaerobic endurance test) in favor of the second experimental group. Recommendations: The Researchers recommend the importance of using Tabata training and modified Tabata training in developing the physical fitness and aerobic and anaerobic abilities of taekwondo players of both gender during different age stages.