Background: New vaccination strategies are needed to control the increasing problem of pertussis in teenagers and adults. Aim: To determine the immunogenicity and reactogenicity of a diphtheria-tetanus-acellular pertussis (dTpa) vaccine with reduced antigen content. Material and Methods: A single dose of the dTpa vaccine was administered to 60 children 10 to 11 years old and 60 healthy adults. At the moment of vaccination and one month later, antibody levels were measured against 3 B pertussis antigens: anti-pertussis toxin (PT), anti-pertactin (PRN) and anti-filamentous hemagglutinin (FHA), as well as anti-tetanus and anti-diphtheria antibodies. Local and general symptoms were registered during 14 days following vaccine administration. Results: Antibody response for PT, FHA and PRN was 98.3%, 100% and 100% in adults and 98.2%, 100% and 98.2% in children. Seropositivity for all pertussis antigens was 100% in adults and in children one month after vaccination. Geometric mean titers (GMT) significantly increased in adults and children. The seroprotection level achieved for tetanus and diphtheria antibodies one month after vaccination was 96.7% for adults and 100% for children, respectively. No serious adverse events were reported during the study. Among local symptoms pain was the most frequent (88-90%), but it was mostly mild or moderate. Solicited general symptoms observed for children and adults, respectively, included headache (37% and 53%), fatigue (18% and 35%) gastrointestinal symptoms (18% and 25%) and fever (8% and 3%). Only one vaccinee had fever above 39°C. Conclusions: the dTpa vaccine showed an adequate safety profile and induced an intense immunological response to all antigens in adults and children aged 10-11 (Rev Méd Chile 2002; 130: 502-10)