Hodgkin lymphoma (HL) treatment protocols for adolescents and young adults traditionally vary by age, but the biological and clinical rationale for this remains uncertain. Our aim was to investigate clinical presentation and outcome in different age groups (0-9, 10-17, 18-24 years) and to compare prognosis among patients treated in pediatric or adult departments. PATIENTS AND METHODS 1345 classical HL (cHL) 0-24 years were diagnosed in Denmark 1990-2010 and Sweden 1992-2009. Disease characteristics and treatment outcome were available for 1083 cHL patients treated in pediatric (n=325) or adult departments (n=758). Outcome was estimated as event free survival (EFS) and overall survival (OS) and using Cox regression. Patients treated in adult departments were mainly treated with ABVD (doxorubicine, bleomycin, vinblastine, dacarbazine) or BEACOPP (bleomycin, etoposide, doxorubicine, cyclophosphamide, vincristine, procarbazine, prednisone) +/- radiotherapy (RT) and the majority of the pediatric patients with OPPA/OEPA (vincristine, etoposide vs procarbazine, prednisone, doxorubicine) and COPP/COPDAC (cyclophosphamide, vincristine, prednisone, procarbazine vs dacarbazine) +/- RT. RESULTS Children0-9yrs had male predominance and presented with lower stage disease and lower frequency of B-symptoms and extra nodal disease. Five-year EFS was lower among Danish paediatric patients (0-14 years) [0.81 (95% confidence interval (95%CI):0.72-0.88)] than among Danish adults [0.85 (0.81-0.88)], Swedish pediatric patients (0-17 years) [0.89 (0.85-0.93)] and adults [0.90 (0.86-0.92)] (Figure 1A). There was no difference in 5- or 10-year OS (Figure 1B). Danish pediatric patients received RT (32%) less frequently than Swedish pediatric patients (71%), p<0.002, while in adults the difference was not as pronounced (Denmark 67%, Sweden 56 %). In analyses adjusted for sex, stage and country, EFS and OS did not vary among patients treated in pediatric compared to adult departments. CONCLUSION Children0-9yrs had a different clinical presentation in several aspects, whereas adolescents10-17yrs and young adults18-24yrs shared similar features. There was no difference in treatment outcome between pediatric and adult departments overall. Patients in Denmark treated in pediatric departments had lower EFS than patients in Swedish pediatric departments and Swedish and Danish adult departments. This correlated to a lower use of RT in primary treatment. OS was equal between the groups.