【Abstract】Peripheral Tcell lymphoma, not otherwise specified (PTCLNOS)is a biologically and clinically heterogeneous disease. PTCLNOS is diagnosed on an exclusion basis as a disease whose features are not consistent with any of the other PTCL subtypes defined by the World Health Organization classification.Gene expression profiling has improved the diagnosis of PTCLNOS.Although the best firstline approach is not to be defined, anthracyclinecontaining regimens,mainly CHOP,followed by auto SCT are regarded as the standard in transplanteligible patients. Several new drugs are active in relapsed and refractory patients, although these drugs do not significantly affect survival rates. Whether these drugs can be safely and efficiently combined with CHOP in newer firstline regimens is under investigation.