Objectives: Porphyromonas gingivalis has been implicated as a major pathogen for adult periodontitis. P. gingivalis has a high adherence activity to erythrocytes and epithelial cells , and hemagglutinin has been identified as an important virulent factor. Hemin is an absolute requirement for the growth of this bacterium. Thus, hemagglutinin molecule may be particularly important for adherence of this microorganism not only to gingival tissue cells, but also to attach and lyse erythrocytes in order to uptake hemin. When considering passive immunization against periodontal diseases, the pathological focus should be on gingival tissues, and application of a specific antibody that neutralizes colonization onto gingival tissue and hemin uptake is significant, and hemagglutinins are considered the most important targets for passive immunization. We previously cloned the 130-kDa hemagglutinating domain (130k-HMGD), and the functional short motif in 130k-HMGD was determined as PVQNLT. Recently, IgY has attracted considerable attention as an alternative source of antibodies for the advantage of cost-effectiveness and large-scale preparation. To develop immunotherapy against periodontitis, IgY against 130k-HMGD which capable inhibiting hemagglutinationwas constructed. Methods: Recombinant 130k-HMGD (r130k-HMGD) was largely expressed by E. coli and purified. Hens were immunized with highly purified r130k-HMGD intramuscularly and after the antibody titer reached to the highest level, the egg-yolk was pooled and the IgY was purified using a ă-carrageenan method. Hemagglutinating activity was assayed in round-bottom microtiter plates using rabbit erythrocytes. Results: The purified IgY from the immunized egg-yolk specifically recognized r130k-HMGD and also reacted with chemically synthesized functional hemagglutinin-associated short motif peptide. As expected, the IgY significantly inhibited P. gingivalis-associated hemagglutinating activity. Conclusion: Anti-r130k-HMGD IgY may be useful for passive immunization against periodontal disease caused by P. gingivalis infection .