The purpose of this study was to determine the effects of student and teacher gender on 9th grade students' in-class physical activity. In-class physical activity was measured in 43 classes taught by 8 female and 7 male teachers. Male students were more active than females (F(1,243) = 23.774, p < 0.001). But, students of female teachers were more active (M = 3.293 ± .734, F(1,243) = 20.243, p < 0.001) than those of male teachers. Students of female teachers were more active in all 5-E instructional segments than students of male teachers (E1, E2, E3, E5: p < 0.001; E4: p = 0.011). The findings indicate a need to address the teacher perception of gender roles in physical education.