Primary effusion lymphoma (PEL) is a rare but aggressive form of non-Hodgkin's B-cell lymphoma in immunodeficient patients. Resistance to conventional chemotherapeutic regimens is common in PEL and contributes to a very poor prognosis; hence, novel potent anti-PEL agents are required. Anticancer effects of non-steroidal anti-inflammatory drugs (NSAIDs) are well-established in epithelial cancer but are unclear in hematological malignancies. Therefore, the anticancer activities of selected NSAIDs, sodium salicylate (NaS), on PEL cell lines are of interest. Anti-proliferation of NaS on PEL cell lines was shown by MTT. Apoptosis induction and caspase activations were determined by flow cytometry analysis. ROS production was accessed by DCFH-DA. Western blot was performed to determine molecular mechanisms. NaS effectively inhibited cell proliferation of all PEL cell lines. Caspase-dependent apoptosis was demonstrated and simultaneous induction of reactive oxygen species production and c-Jun N-terminal kinases (JNK)-p38 activation was observed prior to apoptosis induction, and these might be responsible for NaS-induced apoptosis. Significant anticancer effects of NaS on PEL cell lines were found. A novel role of NaS for PEL treatment is suggested.