Plasmablastic lymphoma (PBL) is a rare and aggressive variant of diffuse large B-cell lymphoma predominantly in oral cavities of human immunodeficiency virus (HIV)-positive male patients or immunosuppressive hosts. Limited number of reports on HIV-negative PBL in immunocompetent patients are available in the literature. We reported an unusual case of sinonasal PBL which occurred in an HIV-negative and immunocompetent female patient. She underwent endoscopic removal of the tumor and completed 6 cycles of chemotherapy (hyperfractionated-CVAD). Any finding in favour of tumour recurrence was not observed in positron-emission tomography scan (PET-scan) performed 18 months after the treatment.