Purpose: The aim of this study was to investigate the effect of basic tennis education on stress and assertiveness levels among middle school students. Material: The study group consisted of a total of 120 students, 60 females and 60 males, aged 9-11 years. The Rathus Assertiveness Schedule and the Perceived Stress Scale for Children were used as data collection tools, and a questionnaire was administered to gather demographic information of the participants. The data were transferred to IBM SPSS 25.0 package program and analyzed using paired samples t-test. Results: As a result of the statistical analyses performed on the data obtained in the pretest and posttest at p<0.05 significance level, significant differences were found between assertiveness and stress scores of the male participants; between assertiveness and stress scores of the female participants; and between assertiveness and stress scores of the whole study group regardless of gender differences. Conclusions: Pretest and posttest results revealed that there was a significant effect of basic tennis training on the increase in assertiveness levels and the decrease in stress levels among female and male students (p <0.05).