The purpose of this study was to better define the clinical features and natural history of peripheral T-cell lymphomas (PTCL) entities included in the Revised European American lymphoma (REAL) classification. Cases of PTCL were retrieved from the records of the Department of Pathology and classified according to the REAL classification. In addition, cases of anaplastic large cell lymphoma (ALCL) were divided into classical, small cell, and primary cutaneous subtypes, and immunostaining for the anaplastic large-cell kinase (ALK) protein was performed on all cases of ALCL. Clinical features, response to therapy and survival were abstracted. Ninety-two cases of PTCL with adequate clinical information were retrieved. There were 40 cases of ALCL (30 classical, 7 small cell variant, 3 primary cutaneous), 28 PTCL, unspecified, 13 angioimmunoblastic T-cell lymphoma and 11 with other entities. The patients had a median age of 48 years with a range of 6-84 and had an estimated overall survival (OS) of 49% and progression-free survival (PFS) of 22% at 5 years. The International Prognostic Index (IPI) was a significant prognostic factor for both progression-free and OS. Histology was a significant predictor of PFS with anaplastic large cell having the best prognosis. ALK expression was not associated with an improved progression-free or overall-survival in patients with systemic T-cell ALCL. In conclusion, the REAL classification describes distinct PTCL entities. The IPI is the most important predictor of progression-free and OS in patients with PTCL. ALK expression may not provide prognostic information for systemic ALCL.