Background: Adolescents and young adults (AYA) with cancer have less favorable outcomes than other populations for lymphoid malignancies. Pediatric patients have a better survival rate for lymphoid malignancies and current evidence suggests that asparaginase plays a role in improved response to treatment. This study aimed to evaluate if AYA patients at a pediatric hospital were more likely to experience PEG-asparaginase (PEG-ASP) related adverse events than younger patients. Methods: A retrospective chart review from 2007-2017 was conducted in the pediatric population at the Children’s Hospital of Eastern Ontario (CHEO). Only patients having received PEG-ASP were included. Event incidence and risk related to age at diagnosis was assessed through parameter estimates and Wald Chi Square analysis. Results: In total, 75 adverse events were observed: 34/186 (18.3%) experienced allergic reactions, 8/186 (4.3%) pancreatitis, 31/186 (16.7%) thrombosis and 2/186 (1.1%) hemorrhage. 182 patients had complete information for inclusion in in our model. A correlation between age at diagnosis and higher risk of allergic reaction (p<0.001) and pancreatitis (p<0.035) was observed. Conclusion: Allergic reaction and pancreatitis upon administration of PEG-ASP have a higher risk of occurrence as age of diagnosis increases. This includes the AYA population and warrants precaution as PEG-ASP is included in older populations treatment regimens at pediatric centers.