Poor adherence to 6-mercaptopurine during acute lymphoblastic leukemia (ALL) therapy increases relapse risk. Clinically-significant non-adherence has been documented in up to 30% of children treated for ALL on Children’s Oncology Group trials. Whether non-adherence rates vary across regimens with different chemotherapy schedules and modes of administration is not known. In a cross-sectional survey study of N= 61 children treated on, or as per Dana-Farber Cancer Institute (DFCI) ALL Consortium Protocol 11-001, 25% (95% CI 14 – 37%) of respondents self-reported non-adherence to 6MP, suggesting that the frequency of non-adherence may be similar across different Consortia regimens.