We evaluated some immunological parameters in a group of 24 patients affected with myotonic dystrophy (MD). IgG, IgA, IgM immunoglobulin serum levels resulted decreased in most of the patients. Anti-smooth-muscle antibodies have been found in 10 out of 24 patients (45.5%). Moreover in some of them decreased C3 and C4 complement fraction serum levels have been found. Our data confirm the existence of some immunological abnormalities in a great number of subjects affected with the disease. Besides, these data evidence for most of the subjects the presence of autoantibodies non-organ-specific direct against myocellular antigens. These autoantibodies could be considered the expression of suffering of muscular fibres.