To evaluate in a prospective multicenter trial the feasibility and clinical efficacy of the combination of alemtuzumab (Campath-1H) with the cyclophosphamide/doxorubicin/vincristine/prednisone (CHOP) regimen (CHOP-C) as the primary treatment for patients with peripheral T-cell lymphoma (PTCL), between January 2003 and December 2005, 24 consecutive patients with PTCL entered the study and received 8 CHOP courses. Alemtuzumab was added at 30 mg subcutaneously at day −1 initially to the first 4 courses (4 patients), and then to all 8 courses (20 patients). Complete remission (CR) was achieved in 17 (71%) patients, 1 had partial remission, and 6 had stable/progressive disease. At a median follow-up of 16 months (range, 5-42 months), 14 patients were alive, 9 had died from progressive disease, and 1 had died from pneumonia at day +198 while in CR. So far, 13 are disease-free, with an overall median duration of response of 11 months. The most frequent side effects were grade 4 neutropenia and cytomegalovirus (CMV) reactivation. Major infections were Jacob-Creutzfeldt (J-C) virus reactivation, pulmonary invasive aspergillosis, Staphylococcus sepsis, and pneumonia. This study shows that CHOP-C: (1) is a feasible chemoimmunotherapy regimen; (2) is effective in PTCL with a high rate of CR achievement; and (3) is associated with mostly manageable infectious complications. This clinical trial was registered with the Osservatorio Nazionale sulla Sperimentazione cinica as ID no. 141202.