The primary purpose of this study was to describe how students spend their time in physical education classes in the Korean high schools. In particular, regard was paid to pupil Motor Engagement Time (MET), and an additional purpose of this study was to identify gender differences in MET according to grade levels. In much of the literature it has been found that time-on-task variables bear a positive relation to student achievement. Pupil MET has been considered a key learning variable in effective teaching based on this positive relationship. However, this variable has not been investigated in any educational setting in the Korean high school. This study aims to remedy this situation by describing actual student behavior in physical education classes in the Korean high school. Ten high schools in the Seoul metropolitan area and 30 physical education classes were observed and coded using videotapes. The adapted BESTPED coding system was used in this study. It consists of nine behavioral categories, including MET categories-practice, game playing, and exercise. The quantitative and qualitative approaches used in this study are based on the research questions which this study is trying to answer. Quantitative' data were collected by using the five second interval coding techniques in thirty videotaped physical education classes. Qualitative data were collected through live observation, formal and informal interviews with 9 physical education teachers. This study showed that the overall pupil MET in the sample classes was 32.3%. and the waiting time was 32.9% in the sample classes. The proportion of waiting time is very high considering that such time is essentially wasted in physical education classes. A 2 × 3 Analysis of Variance: (ANOVA) showed significant (P＜0.05) differences in MET between boys and girls. In addition, there was also a significant (P＜0.05) mean difference in pupil MET scores among grade 10, grade 11, and grade 12. Teaching style and teacher attitude contributed to a positive or negative levels of pupil MET in the Korean high school setting. In addition, facilities and student-teacher ration also influenced pupil MET in both negative and positive ways. Some of the key variables influencing waiting time included inadequate facilities and equipment, poor organizational skills, and large student-teacher ratio.