The mechanism of cavernous sinus involvement by metastatic carcinoma from a facial primary tumor is poorly understood. The lack of lymphatic and obvious direct extension implicate either a vascular or perineural method of spread. The authors describe four patients who exhibited cavernous sinus metastases from facial carcinoma, all of whom experienced cranial nerve symptoms before the diagnosis of cavernous sinus involvement was made. Furthermore, the pathologic specimens from these patients exhibited extensive perineural involvement. The authors propose that the mechanism of metastasis in these patients is perineural extension.