BACKGROUND: T-cell acute lymphoblastic leukemia (T-ALL) remains understudied compared to B-cell ALL, especially in Latin America. Different biology and response to chemotherapy have been described. METHODS: This retrospective multi-site cohort study analyzed data from 152 newly diagnosed T-ALL patients aged 15 years and above, between January 2010 and June 2022. RESULTS: The median age was 30 years, with 53.9% of the patients presenting thymic T-ALL. Asparaginase-based regimens were used in 80.5% of patients. Five-year overall survival (OS) and event-free survival (EFS) were 44.3% and 41%, respectively. Thymic (CD1a) phenotype (HR 0.50 [0.28-0.89], P = .019) and asparaginase-based regimens (HR 0.53 [0.32-0.88], P = .014) were associated with improved OS, while older age predicted inferior OS (HR 1.02, P = .017). The 60-day cumulative incidence of thrombosis was 19.5% and induction death rate of 11.2%. CONCLUSIONS: The study provides real-world multicenter Brazilian data on adult T-ALL, which might represent Latin America's scenario, also highlights the benefits of pediatric-inspired regimens, especially for younger adults, key prognostic factors and that awareness is needed to manage thrombotic/death risks in the early treatment phases to improve outcomes.