Background We characterized the incidence of central nervous system (CNS) involvement, risk factors and outcome in a large single institution dataset of peripheral T-cell lymphoma (PTCL). Methods Retrospective review of the PTCL database at Memorial Sloan Kettering Cancer Center. We identified 231 patients with any subtype of PTCL between 1994-2011 with a minimum six months of follow-up or an event defined as relapse or death. Results Histologies included peripheral T-cell lymphoma-not otherwise specified (PTCL-NOS) (31.6%), angioimmunoblastic (16.9%), anaplastic large cell lymphoma (ALCL), ALK- (12.1%), ALCL, ALK + (6.1%), extranodal NK/T-cell lymphoma (7.4%), adult T-cell leukemia/lymphoma (ATLL) (7.4%), and transformed mycosis fungoides (8.7%). Seventeen patients had CNS disease (7%). Fifteen had CNS involvement with PTCL and two had diffuse large B-cell lymphoma and glioblastoma. Median time to CNS involvement was 3.44 months (0.16-103.1). CNS prophylaxis was given to 24 patients (primarily intrathecal methotrexate). Rates of CNS involvement were not different in patients who received prophylaxis. Univariate analysis identified stage III-IV, bone marrow involvement, >1 extranodal site and ATLL as risk factors for CNS disease. On multivariate analysis, >1 extranodal site and international prognostic index (IPI) ≥ 3 were predictive for CNS involvement. The median survival of patients with CNS involvement was 2.63 months (0.10-75). Conclusions Despite high relapse rates, PTCL, except ATLL, carries a low risk of CNS involvement. Prognosis with CNS involvement is poor and risk factors include: >1 extra nodal site and IPI ≥3.