The sexual adaptation of 48 single young adults with cystic fibrosis and a comparably aged single group without chronic disease was assessed using interviews and questionnaires. The patients were also compared to a previously studied group of married patients with cystic fibrosis. Single female patients with cystic fibrosis began dating later, dated less often, felt less attractive, had less sexual desire, and had more sexual problems than did physically healthy female subjects. Single male patients with cystic fibrosis seemed to fare far better than their female counterparts and approximated the healthy male group in all parameters studied. For both the single and married groups with cystic fibrosis, no significant relationship between the severity of disease and sexual health was evident. The single patients were diagnosed at a significantly earlier age and their general health scores were poorer than the married patients. The vulnerability of female patients with cystic fibrosis to psychosexual disruption suggests that attention be focused on the differential effects of other chronic illnesses upon male and female adult sexual adaptation.