Enterobacteriae with R factor were isolated from faeces of 113 children interned in the Instituto de Puericultura da U.F.R.J. and Hospital Jesus in the periods of 1960-1964 and 1970-1973. The results obtained show that a high percentage og the children 71,6% eliminated resistant bacterias of wich 41,3% was resistant to one drug and 58,7% was resistant to various drugs.