This research intends to investigate the effect of sleep quality and physical activity on cardiorespiratory fitness of students of Faculty of Sports Science (FIK) UNY. The research method used was survey which used questionnaire and measurement tests. The measurements involved several instruments: Pittsburgh Sleep Quality Index (PSQI) was used to measure sleep quality; Global Physical Activity Questionnaire (GPAQ) was used to measure physical activity; multi stage fitness test was used to measure cardiorespiratory fitness. The research population was FIK students. Data analysis technique employed regression test. The research result indicates that both sleep quality and physical activity have a significant effect on physical fitness.