We demonstrated in this study that blood group O subjects attracted more Aedes albopictus than other blood groups (B, AB, and A) but were only significantly more attractive than blood group A subjects in 64 human landing tests. We collected saliva from the subjects and tested it for agglutination inhibition, categorized the subjects into secretors or nonsecretors, and studied mosquitoes' landing preferences for those groups. The mean relative percent landing on blood group O secretors (83.3%) was significantly higher than on group A secretors (46.5%). We also compared the attraction to subjects according to blood groups using forearm skin treated with ABH antigens. Blood group O disaccharide (H antigen) attracted significantly more Ae. albopictus than did blood group A trisaccharide (A antigen), and subjects treated with blood group A disaccharide attracted significantly more Ae. albopictus than did subjects treated with blood group B trisaccharide (B antigen), but ABH antigens did not, in general, influence the landing preference of mosquitoes among ABO blood groups.