10 patients with paroxysmal nocturnal hemoglobinuria were studied taking 109 normal subjects of the Cuban population as control group. 26 HLA antigens corresponding to loci A and B were studied in both groups. Phenotypical frequency of both groups were compared. No statistically significant increase was found for any of the studied antigens, though there was a nonsignificant increase for antigens HLA-B7 and BW-21. These results might be influenced by the small number of patients studied due to the rareness of the disease.