The infection caused by the rubella virus is a mild disease usually with no or rare complications in children and adults. On the contrary, intrauterine fetal infection may result in defects of the child, which may either be present at birth or become apparent later in life. Such a risk led to the preparation and use of active immunoprophylaxis against rubella in females of child-bearing age, in order to prevent congenital rubella. Three rubella viruses are employed to prepare the vaccine, all derived from the same viral strain. Doubts however, exist about vaccination, in particular about (1) its teratogenic potential in pregnancy; (2) the duration of protection. As a matter of fact, congenital malformations in the fetus exposed to vaccine virus through the mother have been reported in 3% of cases. As to the second point, the data on the protective immunity in time of the vaccine are very controversial. It is clear, anyhow, that protection against infection is associated not only with persistence of adequate serum levels of antibody, but also with other immunological parameters which are still unknown. These considerations, together with the observation that a relative high percentage of vaccine recipients do not respond, lead us to suggest modifications in the present scheduling of immunization against rubella.