Oligonucleotide primers were used to amplify specific DNA regions of the Bordetella pertussis genome by the polymerase chain reaction. One pair of primers, PTp1/PTp2, identified a 191-bp DNA fragment located in the regulatory region of the pertussis toxin operon; a second pair of primers led to amplification of a 121-bp DNA piece located in an insertion-like element specific to B. pertussis. Both sets of primers were able to discriminate between the pathogen and related Bordetella species; they detected down to 6 bacteria and appeared suitable for routine detection of B. pertussis in clinical specimens.