Background: Fatigue was recently reported to be the largest contributor to poor health-related quality of life (HRQOL) in paediatric Duchenne muscular dystrophy (DMD). Additional studies are necessary to confirm the generalizability of this finding. Our objective was to explore the longitudinal relationship between fatigue and HRQOL in an additional cohort of DMD patients. Methods: We performed a secondary analysis of data from a clinical trial (NCT00592553), which enrolled patients with nonsense mutation DMD, aged 5–20 years, from 37 sites in 11 countries (N=174). Fatigue and HRQOL were assessed using the PedsQLTM Multidimensional Fatigue Scale and Generic Core Scales, respectively, by patient- and parent-report at baseline and over 48 weeks. Results: Patients reported greater fatigue than healthy controls from published data. There was no significant difference between patient- and parent-reported fatigue. Fatigue was significantly correlated with worse HRQOL at baseline, by patient-report (r=0.70, P<0.001) and parent-report (r=0.70, P<0.001); and at 48 weeks, by patient-report (r=0.79, P<0.001) and parent-report (r=0.74, P<0.001). Change in fatigue was significantly correlated with change in HRQOL over 48 weeks, by patient-report (r=0.64, P<0.001) and parent-report (r=0.67, P<0.001). Conclusions: Fatigue is a major contributor to HRQOL in DMD. The strong association between fatigue and HRQOL corroborates previous studies, and suggests that reducing fatigue may improve HRQOL.