Nasal-type natural killer/T-cell lymphoma (nasal NKTCL) is an aggressive hematological neoplasm with poor prognosis, and its incidence is higher in Asia than in Western countries. Increasing evidence suggests that aberrant activation of signal transducers and activators of transcription 3 (STAT3) is related to numerous malignancies. However, the involvement of STAT3 in the pathogenesis of nasal NKTCL is poorly understood. In this study, immunohistochemistry (IHC) showed that 21/28 (75.0%) nasal NKTCL tissues harbored constitutively expression of phospho‑STAT3 (p‑STAT3) which was positively correlated with the Ki‑67 levels (P﹤0.05). Immunofluorescence (IF) also detected p‑STAT3 expression in SNK6 cells (NKTCL cell line). Furthermore, WP1066 (a novel selective STAT3 inhibitor) was able to inhibit proliferation and induce apoptosis of SNK6 cells. Moreover, western blot analysis and RT‑PCR demonstrated that WP1066 downregulated the protein and mRNA expressions of the pro‑survival molecules (including c‑Myc, cyclin D1, and Bcl‑2) in SNK6 cells. These results suggested that STAT3 activation represents a potential target in nasal NKTCL. WP1066 may be a promising agent in antitumor therapy against nasal NKTCL.