Seventy-four (50 females and 24 males) consecutively sampled patients with otosclerosis were tissue typed for HLA A and B antigens. There was no significant increase in any A or B antigen, but the frequency of B40 was significantly lower (p less than 0.05) in patients than in blood donors. No significant difference in HLA antigen frequencies was found between men and women, or in patients with vs. without a family history of otosclerosis.