Combination vaccines allow the administration of multiple vaccine antigens without the need for multiple injections. Recently, a combined diphtheria toxoid, tetanus toxoid, acellular pertussis and inactivated poliomyelitis vaccine (DTaP-IPV), Kinrix, has been licensed in the USA for use as the fifth DTaP dose and fourth IPV dose in children 4-6 years of age. Clinical trials have shown Kinrix to be immunogenic in 4-6-year-old children, with a safety profile comparable with that of separate DTaP and IPV vaccination. The use of Kinrix reduces by one the number of injections required to provide this age group with all recommended immunizations. Strategies such as the use of combined vaccines can help to maintain high levels of coverage against diphtheria, tetanus, pertussis and poliomyelitis diseases.