Angioimmunoblastic T-cell lymphoma (AITL) is a major type of peripheral T-cell lymphoma (PTCL). To elucidate the clinicopathologic characteristics and prognosis of AITL in Japan, we retrospectively analyzed 207 patients with AITL. The median patient age was 67 years (range, 34-91 years), with 73% of patients older than 60 years. With a median follow-up of 42 months in surviving patients, 3-year overall survival (OS) was 54% and progression-free survival (PFS) was 38%. The International Prognostic Index (IPI) and the prognostic index for PTCL, not otherwise specified (PIT) were predictive for OS in this analysis. Multivariate analysis found that age older than 60 years, elevated white blood cell (WBC) and IgA levels, the presence of anemia and thrombocytopenia, and extranodal involvement at > 1 site were significant prognostic factors for OS, and IgA, anemia, and mediastinal lymphadenopathy were significant prognostic factors for PFS. A novel prognostic model consisting of the prognostic factors for OS was successfully constructed. In conclusion, IPI and PIT were still useful for prognostication of AITL, and other factors, including those not used in IPI, such as IgA, anemia, WBC count, thrombocytopenia, and mediastinal lymphadenopathy, also significantly affected prognosis. Future investigations for IgA as a unique prognostic factor are warranted.