In order to determine if there was an association of pemphigus vulgaris and any antigenic specificity of the HL-A system, 43 unrelated white patients with pemphigus vulgaris were typed for HL-A by the microdroplet lymphocyte cytotoxicity test. HL-A10 was present in 17 of 28 unrelated Jewish patients with pemphigus vulgaris (60.7%) as compared to 19 of 94 Jewish control patients (20.2%) (P<.0001). Among female patients, the occurrence of HL-A10 was 71% and among male patients, 45%. HL-A10 was elevated but not significantly associated with pemphigus vulgaris in non-Jewish whites. No significant associations were noted for other HL-A specificities. A pemphigus susceptibility gene linked to HL-A is postulated.