This study investigated agreement between boys and their parents when reporting on health-related quality of life and the effects of steroid use, age, and physical functioning on self-reported health-related quality of life in boys with Duchenne muscular dystrophy. The Pediatric Quality of Life Inventory™ and brief functional measures were administered to 35 parent-son dyads. We found that agreement between parents and their sons was moderate (intraclass correlation coefficient [ICC](2,1) = 0.66; 95% confidence interval [CI], 0.40-0.80) to poor (ICC(2,1) = 0.64; 95% CI, 0.43-0.64). The boys' self-reports revealed a relationship between disease progression and physical functioning (r = -.75; P = .01); however, disease stage was not related to psychosocial functioning (r = -.27; NS). Parents and boys affected by Duchenne muscular dystrophy have a moderate to poor agreement on health-related quality of life measures, with parents reporting lower overall health-related quality of life when compared with their sons.