To assess the association between open‐angle glaucoma and HL‐A antigens, the frequencies of 25 HL‐A antigens were determined in 49 patients with OAG and 22 patients with increased intraocular pressure, due to causes other than OAG, using the microcytotoxicity method. The results were compared to 250 individuals from the general population who were tested in the same laboratory at the same period of time. Using rigid statistical analysis, the incidence of the Bw35 antigen was found to be significantly (≪0.012) higher among OAG patients. In a group of 27 first relatives of OAG patients who were tested at the same time, the frequency of Bw35 antigen was increased compared to the general population. The biological importance of the association between Bw35 and OAG, which may still be a chance deviation, is not yet fully understood. It may indicate that the Bw35 antigen or the HLA loci are among the genetic factors which produce susceptibility to open‐angle glaucoma.