SummaryBurkholderia cepaciahas become an increasingly recognized pathogen among cystic fibrosis (CF) patients and its potential role in declining pulmonary function or unexpected fatal outcome has caused widespread concern. Direct person-to-person transmission has been documented and a segregation policy of CF patients colonized withB.cepaciafrom non-colonized CF patients is widely adopted. Since this policy has a dramatic impact on social behaviour of CF patients it is imperative that clinical laboratories accurately isolate and identifyB.cepaciain the respiratory secretions.In order to comprehend the epidemiology ofB.cepaciain the Belgian CF population a multicentre study was conducted during a period of 1 year (March’93-February’94).B.cepaciawas isolated in only 12 of 465 CF patients (2.6%). Roudne biochemical tests identified these strains as authenticB.cepacia.However, the combined data from protein and DNA-DNA hybridization analyses revealed that the Belgian CF“B.cepacia”isolates showed patterns different from referenceB.cepaciaisolates and belong to 3 different, newly identifiedBurkholderiagenomovars, but not toB.cepacia.