The identification of a possible autoimmune etiology for a sensorineural hearing loss (SNHL) is essential for a successful medical treatment. Confirmation of diagnosis in clinically "high-risk" patients is provided by antigen-specific tests, which are not easily obtainable on a routine basis in the otologic clinic; on the other hand the reliability of non-specific-antigen tests is questioned. The outcome of serological tests in a group of patients with possible autoimmune SNHL were compared with those obtained in two control groups, one of normal subjects and one with systemic autoimmune disorders. The test battery included the dosage of circulating aspecific autoantibodies (anti-nuclear, anti-perinuclear factor, anti-mitochondrial, anti-smooth muscle), the total haemolytic activity (CH50), the immunoglobulin fractions and the aspecific inflammation indexes. At the p level of 0.05, none of the findings reached statistical significance, except for low CH50 in 31% of SNHL patients. Complement consumption is an indirect indicator of the presence of immunocomplexes. The serum dosage of the total haemolytic activity is suggested as screening. Investigation to detect circulating immunocomplexes is to be extended to patients with low CH50 levels.