The present study includes a Norwegian sample of 15-year-old students (N = 1,670) and is part of a World Health Organization cross-national survey, Health Behavior in School-Aged Children (Currie, 1998). The objective was to examine the relationship between school-related stress, leisure time physical activity, and adolescent health complaints. Physical activity was also examined as a moderating variable in the relationship between school-related stress and health complaints. The results showed that high levels of complaints were associated in a linear relationship with high levels of school-related stress and low levels of leisure time physical activity. Reports of complaints were more closely related to stress for adolescents with low levels of physical activity; thus, physical activity seems to moderate the relationship between school-related stress and health complaints.