Case report: olfactory loss and unrelated chronic rhinosinusitis. A case is presented in which a meningioma of the olfactory region caused olfactory loss as the only presenting symptom. Diagnosis was delayed by the presence of mild chronic sinusitis, presumed to have been responsible for the presenting hyposmia. The meningioma was initially not detected on a CT scan of the sinuses. A well conducted anamnesis and objective assessment of total anosmia through smell identification tests raised the suspicion of a sensorineural olfactory disturbance. The tumour was finally diagnosed on MR imaging. The paper discusses the practical management of patients presenting with olfactory dysfunction.