Non-traumatic nasal septal abscesses (NSAs) are rare and those associated with acute sinusitis are even rarer. We report a case of a 12-year-old female child with NSA and complicating acute spheno-ethmoiditis that was diagnosed by physical examination and computed tomography (CT) scan. The NSA was treated by surgical incision and drainage of the abscess, endoscopic aspiration of pus from the spheno-ethmoidal recess, systemic antibiotic therapy, and nasal cleansing.