The primary objective of this study is to examine the acute effects of static stretching applied for different durations on agility, speed, and joint range of motion in taekwondo athletes aged 12-14 years. A total of 24 taekwondo athletes voluntarily participated in the study. The participants' mean age was 13.02±0.51 years, height was 1.51±11.25 cm, weight was 39.80±4.37 kg, and sports experience was 4.35±2.52 years. In addition, it was determined that 62.5% of the participants had a right leg dominant extremity, while 37.5% had a left leg dominant extremity. A cross-controlled experimental design was used on the same group of subjects in the present study. In the study, which was conducted in two different sessions, the subjects were randomly divided into two groups, group A and group B. After a general warm-up, the first group performed a 15-second static stretch, while the second group performed a 30-second static stretch and then performed speed, agility, and joint range of motion tests, respectively. Following the tests, the athletes were given two days of rest. Subsequently, the groups switched places, with the group that performed 15 seconds performing 30 seconds, and the group that performed 30 seconds performing 15 seconds of static stretching. After the stretching exercises, a 4-minute rest period was provided. After the general warm-up, a 10-meter sprint, a Taekwondo-specific T agility test, and joint range of motion measurements (quadriceps and hamstring muscles) were performed, and the results were recorded manually and on a computer. Normality analysis was performed using the Shapiro Wilk test, and the dependent sample t-test was used to analyze the data determined to be normally distributed. The analysis of the data showed a significant difference in favor of those who performed 15 seconds in agility and speed (p>0.05). No significant difference was found in the dominant extremity quadriceps and hamstring muscles as a result of the measurements (p>0.05). A significant difference was found in favor of those performing 30 seconds in the nondominant hamstring and quadriceps joint range of motion parameter (p <0.05). As a result, static stretching for 15 seconds in agility and speed tests and for 30 seconds in the nondominant hamstring and quadriceps joint range of motion parameters is recommended for athletes.