In the province of Ferrara (Italy) a programme for the prophylaxis against some connatal infections has been carried out through a "Service for the epidemiology and prevention of connatal rubella and toxoplasmosis", which has been instituted in 1978. The investigations on two female groups of different age (prepuberal and adult fecund women) have allowed to obtain the following data: 1. rebella infection has a high incidence yet in prepuberal age (10 years) when a percentage of 62.1 women have already acquired a strong immunity; this percentage arises to 85.0 in adult fecund women. The "conversion index" of 22.9 corresponds to the percentage of subjects who have got the infection in postpuberal, "at risk" age; 2. toxoplasmosis has different epidemiological features; its incidence is lower, in prepuberal age (31.7%), while it is higher (63.4%) in adult fecund women. The highest incidence between 15 and 20 years, and the highest "conversion index" (31.7) underline that, notwithstanding its lower infectiousness, the risk of connatal toxoplasmosis is higher than that of connatal rubella, as far as our country is concerned. Such epidemiological investigations are believed to be necessary to carry out a really useful programme for the prevention of connatal rubella and toxoplasmosis.