Purpose: The present study aimed to explore possible factors that have contributed to students' boredom in physical education (PE) lessons. Methods: A total of 19 teachers (53% females and 47% males) and 112 students (50% females and 50% males) from two co-educational primary schools completed a set of questionnaires. A focused group discussion was then conducted with 20 students to further examine the relationship between situational factors and boredom. Results: Findings showed that overall, students highly enjoyed PE lessons and had low levels of anxiety and boredom. However, 20% of the participants agreed that they often experience boredom in PE lessons. In relation to the experience of boredom, a multiple regression analysis revealed that three variables (opportunity costs, monotony, and generalized boredom) were significant predictors of students' boredom scores. Conclusions: The PE teacher ought to consider the set of significant predictors of boredom when developing lesson plans and instructional strategies aimed at alleviating the negative emotional experiences.