t Enzymatic removal of blood groups antigens A and B is an efficient method for production of universal red blood cells. In this research, an a-N-acetylgalactosaminidase (NAGA) enzyme was expressed in Pichia pastoris for digestion of the A blood antigen. DNA sequence of the gene NAGA, originally expressed in Elizabethkingia meningosepticum (NAGA-EM), was ordered for optimization and synthesis. It was then expressed in P. pastoris (KM71H and GS115 strains). Expression of the recombinant NAGA was evaluated by dot blot, SDS-PAGE, and Western blotting. The activity of the enzyme was measured using a synthetic substrate in addition to the conversion of group A red blood cells to the O cells. Expression of NAGA-EM with an apparent molecular mass of 55 kDa was verified by dot blot, SDSPAGE and Western blot analysis. The maximum enzyme activity in the supernatant of KM71H was higher than that in the GS115 (250 vs. 200 U/ml). Treated group A RBCs did not react with the anti-A antiserum or with the sera from individuals with blood groups B and O. The results of this study indicated that NAGA-EM is an efficient enzyme for production of universal O blood cells.