Abstract The epidemiological uncertainties of a terminal illness would seem to prohibit the ritual exchange of faith and hope between patient and medical personnel. However, after interviews with people involved in cystic fibrosis networks, I argue that there exists a process of neutralizing five epidemiological uncertainties of this disease: (1) aetiology; (2) genetics; (3) treatment; (4) societal reaction and (5) life expectancy. This process consists of five techniques corresponding to these five epidemiological uncertainties, respectively: (1) the modification of question; (2) the promise of research; (3) the uniqueness of each case; (4) the comparison with others and (5) the lack of an alternative to therapy. Neutralising the epidemiological uncertainties of this disease serves to support the swaying edifice of faith and hope and enables the people within the network to devote themselves to compliance with cystic fibrosis therapy.