The present study aimed to examine the relationship of mental pressure with optimism and academic achievement motivation among second grade second period male high school students. This study followed a descriptive-correlational method. The sample included 200 second grade second period male high school students in Sooran. Data collection tools in the current study were the Ursula Markham Mental Pressure Inventory (1976), the Tschannen-Moran et al. Optimism Scale (2013), and the Hermans Academic Achievement Motivation Questionnaire (1977). The obtained data was analyzed using both descriptive and inferential statistics (Pearson correlation coefficient and regression analysis) via SPSS software. The results indicated that mental pressure was significantly and negatively related to optimism (P<0.01), such that with an increase in mental pressure, students' optimism decreased. The results of regression analysis revealed that mental pressure predicted 5% of the variance in students' optimism. Moreover, mental pressure was significantly and negatively related to students' academic achievement motivation (P<0.01), such that with an increase in mental pressure, students' academic achievement motivation decreased. The results of regression analysis revealed that mental pressure predicted 4% of the variance in students' academic achievement motivation.