Solitary extramedullary plasmacytoma (SEP) is a rare tumor composed of plasma cells that can develop in any soft tissue of the body. As with all plasma cell disorders, it is a rare disease. This study reports a case of SEP in a 34-year-old male patient who presented with persistent unilateral epistaxis. Endoscopy revealed a hemorrhagic vegetative mass filling the entire right nasal cavity. The mass was extracted endoscopically and was found to originate from the nasal septum. Histopathological examination diagnosed the mass as a plasmacytoma. Systemic evaluation in the hematology department revealed no further foci. During the first year after the surgery, physical examination and radiological investigation found no recurrence or residual disease in the patient. In adult patients with unilateral nasal obstruction and epistaxis, it is important to consider tumoral formations such as SEP.