['An exploratory study has been carried out to assess the association of autoimmune diseases in multiple sclerosis (MS) families with clinical features and disability of MS patients.', 'Age at onset, symptoms and signs at onset, and disability were assessed in 177 patients with definite MS and 178 age- and sex-matched control patients with autoimmune diseases (78 with endocrine and 100 with rheumatological diseases) and correlated with the most frequent autoimmune diseases recorded in the families.', 'Psoriasis was found in 30 relatives of 177 (16.9%) MS patients, thyroid disorders in 17 (9.6%) and allergies in 17 (9.6%). In the control group, psoriasis was found in 22 relatives of 178 (12%) patients, thyroid diseases in 19 (10.7%) and allergies in seven (3.9%). Of the 30 relatives with psoriasis in the MS group, 16 (53.3%) were fathers (P < 0.0001). There was a significant association of high frequency of family psoriasis with early age of MS onset (P = 0.025) but not with onset of symptoms or severe disability.'] Is high frequency of psoriasis in relatives associated with early onset in an Italian multiple sclerosis cohort?