BACKGROUND: The objective was to compare 5-year overall survival (OS) between adolescent and young adult (AYA) patients (age 15-19) with acute lymphoblastic leukemia (ALL) treated at a pediatric versus an adult center. PATIENTS AND METHODS: This was a population-based analysis using administrative data of Ontario ALL AYA patients diagnosed between 1986-2009. We calculated predicted survival proportions (PSPs) and 95% confidence intervals (CI). We also surveyed sites to determine whether pediatric or adult-based protocols were used in each period. RESULTS: Overall, 290 patients between 15-19 years of age were diagnosed with ALL during the study period; 144 patients (49.7%) were treated at an adult center. When adjusted for gender, age, income quintile and time period, AYA patients treated at a pediatric center did not have a significantly different PSP (0.65, 95% CI: 0.56-0.75) in comparison to those treated at an adult center (0.62, 95% CI 0.52-0.73; P = 0.87). Most AYA patients treated at adult centers received pediatric protocols in the recent periods. CONCLUSIONS: Using population-based data, AYA ALL patients had similar outcomes whether treated at a pediatric or an adult center. Early introduction of aggressive treatment protocols in adult centers may have negated differences in outcomes among AYA patients by site of care.