Isolated amyloidomas may, albeit rarely, involve the central nervous system. There are three previous reports of amyloidomas that involved the gasserian ganglion and caused unilateral trigeminal neuropathies. The authors report the case of a 49-year-old woman with apparently isolated amyloidomas that caused slowly progressive bilateral trigeminal neuropathies. Magnetic resonance imaging of the brain revealed mild swelling of the left trigeminal nerve within the cavernous sinus and uniform enhancement with gadolinium throughout the length of the nerve. At craniotomy, the trigeminal nerve and ganglion were observed to be infiltrated by a tumor-like mass. Biopsy showed extensive infiltration of the nerve and ganglion by amyloid. Immunocytochemical studies of the amyloid were negative for immunoglobulins, kappa and lambda light chains, beta-amyloid A4 protein, transthyretin, beta 2-microglobulin, cystatin C, and gelsolin, but weak focal immunoreactivity with antiamyloid AA antibody was seen in the amyloid in vessels and in some intraneural deposits. Extensive investigations failed to reveal evidence of either systemic amyloidoses or an underlying inflammatory disorder or malignancy.