The authors present results obtained by the inoculation in tissue culture of material frorn rectal swabs of susyected paralitic Polio cases, at the Hospital Jesus, at Rio de Janeiro. Among 188 swabs that have been examinated, Poliovírus could be demonstrated in 79 cases (73,5% were positive for type I, 25,3% for type II and 1,2% for type III). An increase of paralitic Polio cases in the last months of 1967 could be demonstrated. Most of the children belong to the age group between zero to 36 months old and were not vaccinated; however, some of the children got one, two or three doses of trivalent vaccine. It is emphasized that serological studies should be done in this area in order to better understanding the multiple factors involved in the response to the vaccination, including the determination of the incidence of non-polio agents in the population.