The pulmonary microbiology is a dominant element in cystic fibrosis and the main cause of death. Contemporary consensus accords an exclusive role in this to a single microorganism, Pseudomonas aeruginosa. The evidence convincingly shows that the microbiology consists of a multiplicity of species living in perpetual interaction and in a variety of forms--planktonic, sessile, anaerobic--and in organized communities as microcosms, biofilms and ecosystem. This compound microbiology, the essence of the pulmonary disease, is of necessity exposed to constant influence both from without (the air) and within (via the blood), leading to a perpetual state of flux with consequent impact on the clinical course. It is perhaps significant that to date, most or all microbiologic studies were probably conducted, classically, with inert instruments (glass? plastic?), whereas in real life the CF microbiology lives in "test-tubes" of live mucosa with which it maintains a permanent "cross-talk." The difference to microbial life between these two media may well be very important. It therefore justifies study and may be far-reaching in its effect. There is persuasive argument to strive for a novel holistic view of the totality of the complex microbiology of CF, and to initiate fresh concepts, strategies and methods.