Pseudomonas aeruginosa is a common and important pathogen in people with cystic fibrosis (CF). With the advent of modern genotyping, a number of clonal strains of P. aeruginosa have been identified, some of which are associated with increased morbidity. The route of cross-infection between people with CF is not clear, but there is evidence that an airborne route may be important. Laboratory studies have shown that P. aeruginosa can survive within droplet nuclei and can potentially remain suspended within aerosols for prolonged periods. Depending upon the air flows, this may result in the bacteria travelling significant distances. A number of clinical studies have demonstrated that people with CF can produce aerosols containing P. aeruginosa and Burkholderia cepacia complex. Infection control guidelines need to consider the possibility of droplet, including small-droplet nuclei, transmission of P. aeruginosa and other pathogens between people with CF. Further studies are needed to more accurately quantify the risk of cross-infection between people with CF and to evaluate interventions to minimize the risk.