With formalinized erythrocytes (FRC) from chickens, men and guinea-pigs, hemagglutination and hemagglutination-inhibition test for myxoviruses with Salk pattern method were studied and the results obtained are as follows.1) Spontaneous agglutination of FRC was prevented with 0.05 per cent bovine serum albumin in the suspending medium.2) There was no or little if any differences between HA- or HI-titers obtained with FRC and those with native red cells.3) FRC was available for HI test after the lyophylization.4) Hemadsorption test in HVJ-infected HeLa cells was successfully performed with FRC without substitution of bovine serum albumin.5) HVJ-adsorpting capacity of FRC was identical with that of native cells, but the eluting capacity was decreased in FRC.6) The ABO-antigenicity of human red cells was partially destroyed by the formalinization.