Familial amyloidotic polyneuropathy (FAP)--Portuguese type, is an autosomal dominant polyneuropathy related with an abnormal transthyrretin (TTR Met 30). In males, the first complaint can be sexual dysfunction. Fifteen FAP patients, mean age 37 +/- 7.7 years, mean disease duration 5.2 +/- 2.2 years, all males, complaining of sexual dysfunction were studied with pudendal evoked potentials (PEP), bulbocavernous reflex (BCR) and sympathetic skin response (SSR). PEP and BCR reflect the central somatosensory pathways and sacral arch functioning; SSR relates with autonomic pathways. The aims of this study were: to correlate clinical and EMG scores with somatic and autonomic fibres involvement; to evaluate the timing of somatic and autonomic nerves lesion in disease evolution. Results showed: that PEP and BCR abnormalities have a statistically significant correlation with clinical and EMG scores; abnormal SSR in the plant precede other clinical or EMG abnormalities in the present study.