Twenty premature-born children received, during their first year of life, vaccines routinely apptied as part of a basic immunization schedule. Sera obtained at the age of 12 months were titered for antibodies against diphteria, tetanus and pertussis. Values considered protective were observed for diphteria and tetanus. Anti - Bordetella pertussis agglutinins were always present, however, in the absence of a consensus as to what are protective levels, no conclusion could be drawn. The present study contributes towards erasing the prejudice and scepticism concerning the immunization of the premature-born.