The author studied by the complement fixation test the influenza virus strains isolated in Rio de Janeiro during the 1973 epidemic. He prepared immunesera in hamsters by the inoculation of the allantoic fluid from infected chick embryos with each of the 7 isolated strains and the standard strains. The soluble antigens were prepared with the allantoic fluid of infected chick embryos. The tests were identically positive with the A2/Hong Kong/68 and A2/England/72 antigens and negative with the B/Mass/66. The tets were type specific and the behaviour of the A2/Hong Kong/68 and the A2/England/72 and the 7 strains of the isolated viruses was almost the same. They fixed 3 or 4 units of complement. The variants PR8, FM1 and Asia fixed only 2 units of complement.