This article has been published previously in Neurosurgical Focus: Marzo SJ, Leonetti JP, Petruzzelli G. Facial paralysis caused by malignant skull base neoplasms. Neurosurgical Focus 2002, Article 2;12(5) ( http://www.neurosurgery.org/focus/may02/12-5-nsf-toc . html). Object Bell palsy remains the most common cause of facial paralysis. Unfortunately, this term is often erroneously applied to all cases of facial paralysis. Methods The authors performed a retrospective review of data obtained in 11 patients who were treated at a university-based referral practice between July 1988 and September 2001 and who presented with acute facial nerve paralysis mimicking Bell palsy. All patients were subsequently found to harbor an occult skull base neoplasm. A delay in diagnosis was demonstrated in all cases. Seven patients died of their disease, and four patients are currently free of disease. Conclusions Although Bell palsy remains the most common cause of peripheral facial nerve paralysis, patients in whom neoplasms invade the facial nerve may present with acute paralysis mimicking Bell palsy that fails to resolve. Delays in diagnosis and treatment in such cases may result in increased rates of mortality and morbidity.