The research aims to identify the relationship between mental alertness and decision-making among karate judges. Karate judges prepared by the two researchers. The researchers used the SPSS V26 program to perform the appropriate statistical treatments (arithmetic mean - standard deviation, skewness, correlation coefficient, f- T test, LSD). The most important results: 1. The presence of statistically significant differences between the rulers in mental alertness according to the degree of judgment, and the presence of statistically significant differences between the rulers in decision-making according to the degree of judgment. 2. There is a positive correlation between mental alertness and decision-making among karate referees. the most important recommendations: Developing the mental alertness of the referees because of their great impact on their ability to make decisions, and the necessity of psychological preparation for the referees of karate sport, in addition to the physical preparation at all levels, attention to the establishment of counseling and psychological courses to refine the referees and the preparation of appropriate programs for them