We examined 44 subject (Group A) of both sexes (27 males and 17 females) aging between 16 and 80 (average: 45+/-16.6), divided into age bands, affected by mild-medium psoriasis with PASI (psoriasis area and severity index) between 1.2 and 48.6 (average: 11.2+/-9.7) without any other disease and we performed pattern transient VEP (Visual Evoked Potential) at the frequencies usually used in clinical experience (73', 36', 18' check size). For a good statistic comparison we choose 55 healthy subjects (group B) divided into age bands on which we performed the same test. Comparison of VEP parameters between psoriatic and healthy subjects, showed in group A 10 normal (22.7%) and 34 pathological (77.3%). In the latter group there are 16 subjects who show only a P100 reduced amplitude (36.3%), 3 with only increased latency (6.8%), 15 with alterations of both values (34%). The achieved data show that more than 3/4 of group A subjects have VEP alterations as index of the presence of a sub clinic optic neuritis with a probably toxic autoimmune origin due to the action of TNFalpha, of IgG, of ECP or of other cytokines (IL6, IL7, etc) that are increased in the blood of this patients. The electro physiologic monitoring of optic nerve seems to represent a good routine test to evaluate the global conditions of psoriatic patients.