Angioimmunoblastic T-cell lymphoma (AITL) is a unique subtype of peripheral T-cell lymphoma (PTCL) with distinct clinicopathologic features and poor prognosis. We performed a subset analysis of 282 patients with AITL enrolled between 2006 and 2018 in the international prospective T-cell Project (NCT01142674). The primary and secondary endpoints were 5-year overall survival (OS) and progression-free survival (PFS), respectively. We analyzed the prognostic impact of clinical covariates and progression of disease within 24 months (POD24) and developed a novel prognostic score. The median age was 64 years, and 90% of patients had advanced stage disease. Eighty-one percent received anthracycline-based regimens and 13% underwent consolidative autologous stem cell transplant (ASCT) in first complete remission (CR1). Five-year OS and PFS estimates were 44% and 32%, respectively, with improved outcomes for patients who underwent ASCT in CR1. In multivariate analysis, age ³60 years, ECOG performance status >2, elevated C-reactive protein, and elevated β2 microglobulin were associated with inferior outcomes. A novel prognostic score (AITL score) combining these factors defined low, intermediate, and high-risk subgroups with 5-year OS estimates of 63%, 54%, and 21%, respectively, with greater discriminant power than established prognostic indices. Finally, POD24 was a powerful prognostic factor with 5-year OS of 63% for patients without POD24 compared to only 6% for patients with POD24 (p<0.0001). These data will require validation in a prospective cohort of homogeneously treated patients. Optimal treatment of AITL continues to be an unmet need and novel therapeutic approaches are required.