The association between sarcoidosis and histocompatibility locus antigens (HLA) (sometimes referred to as human leucocyte antigens) was explored. A total of 174 subjects with sarcoidosis were compared with a reference group of 97 individuals who were free of lung disease. HLA typing of blood samples was accomplished using a two stage microcytotoxicity technique. Blood grouping for the ABO blood types and other blood groups used commercial reagents. The literature on the subject suggested that the antigens HLA-B7, HLA- B8, or HLA-A1 might be associated with sarcoidosis, and these antigens were investigated. The HLA-C antigens had not been tested previously, and they were included in the study. When the participants were grouped by blood type, the only correlation between sarcoidosis and blood type that differed between the patient and reference groups was that the sarcoidosis patients had a lower than expected frequency of the Rh(d)+ blood group. HLA-B8 occurred in 15 percent of the reference group and in 29 percent of the patients with sarcoidosis. The authors conclude that only HLA-B8 shows a statistically significant association with sarcoidosis.