Peripheral T-cell lymphomas (PTCLs) receiving conventional treatment have a poor clinical outcome. We conducted a phase II study to evaluate the feasibility and efficacy of chemo-immunotherapy in young (⩽60 years old, Clin A study) and elderly (>60 and < or =75 years old, Clin B study) patients with newly diagnosed PTCL. Clin A patients (n=61) received two courses of CHOP (cyclophosphamide, adriamycin, vincristine, prednisone)-21 with alemtuzumab (AL, 30 mg) followed by two courses of high-dose chemotherapy. On the basis of donor availability, patients in response received allogeneic (allo) or autologous (auto) stem cell transplantation (SCT). Clin B patients (n=25) received six courses of CHOP-21 and AL (10 mg). Clin A responding patients were 38 of 61 (62%) and received alloSCT (n=23) or autoSCT (n=14); one complete remission (CR) patient was not transplanted. At a median follow-up of 40 months, the 4-year overall survival (OS), progression-free survival (PFS) and disease-free survival (DFS) rates were 49, 44 and 65%, respectively. In Clin B study, the response rate was 72%. At a median follow-up of 48 months, the 4-year OS, PFS and DFS rates were 31, 26 and 44%, respectively. In conclusion, front-line alloSCT or autoSCT is effective in prolonging DFS in young patients; AL in elderly improved response with no survival benefit.