Granzyme B is a serine protease, which mediates the apoptosis signaling pathway of cytotoxic T lymphocytes (CTL) and natural killer cells (NK). Granzyme B is synthesized in the form of inactive protease, stored in lysosomal granules and released during the degradation of effector cells. The results shows that granzyme B is expressed in peripheral T-cell lymphoma (PTCL) and NK cell lymphoma by immunohistochemistry. The expression of cytotoxic proteins may play an important role in the differentiation and classification of peripheral T-cell and NK cell lymphoma, such as granzyme B, because many tumors of this type do not have specific morphology and phenotype.