Peripheral T cell lymphoma (PTCL) is a type of aggressive non-Hodgkin's lymphoma with poor prognosis. PTCL-not otherwise specified (PTCL-NOS) is one of its most common pathological types. PTCL is not sensitive to conventional chemotherapy regimens and treatment is particularly limited in elderly patients due to their poor tolerance to chemotherapy. The present report shares the treatment experience of one elderly PTCL-NOS case, which achieved complete remission by reduced-intensity chemotherapy with chidamide in combination with azacitidine following the onset of organ failure and chemotherapy insensitivity. The 9-month follow-up showed sustained remission and the long-term efficacy of this regimen is also promising.