Because of its potentially serious sequelae, cerebrospinal fluid (CSF) leakage following surgery for lesions of the cranial base is given immediate attention by neurosurgeons. Despite a multitude of approaches used to prevent its occurrence, CSF leakage complicates up to 30% of difficult skull-base tumor operations. The authors describe the cases of 11 patients who developed a syndrome, not previously described in the literature, termed "pseudo-CSF rhinorrhea." This syndrome occurs after surgery of the cranial base, usually involving dissection or removal of the petrous or cavernous carotid artery, the greater superficial petrosal nerve, and the pericarotid sympathetic plexus. It is characterized by nasal stuffiness and nasal hypersecretion and is sometimes accompanied by facial flushing. The symptoms are characteristically exacerbated by exertion or by elevated ambient room temperatures. Lacrimation is typically absent ipsilateral to the pseudo-CSF rhinorrhea. It is believed that pseudo-CSF rhinorrhea developed in these patients because of a relative imbalance of the regulatory autonomic supply of the nasal mucosa.