BACKGROUND:The impact of anxiety and depression on quality of life (QOL) in adult patients with cystic fibrosis (CF) is fully unknown. We investigated the prevalence and factors associated with anxiety and depression, including QOL, in adult CF patients. METHODS: One hundred twenty-one adult CF subjects, age > 18 years were recruited from our out-patient clinic. Participants self-completed the Hospital Anxiety Depression Scale and the Cystic Fibrosis Quality of Life Questionnaire (CF-QOL). Socio-demographic data and values for lung function were extracted from the medical notes. RESULTS: Mean ؎ SD age was 30 ؎ 8.8 years, and age ranged 18 -70 years. Forty (33%) were identified with anxiety symptoms, 20 (17%) with depressive symptoms. Factors related with depression were impaired QOL and low lung function. Anxiety was associated with difficulty in interpersonal relationships and severity of chest symptoms. The CF-QOL subdomains (physical functioning, social functioning, treatment issues, chest symptoms, emotional functioning, concerns for the future, interpersonal relationships, body image, future/career concerns, and total CF-QOL) were all significantly correlated with anxiety (P < .001) and with depression (P < .001), respectively. CONCLUSIONS: Anxiety and depressive symptoms are common in adult CF patients. They are associated with poorer QOL, low lung function, reduced physical functioning, and severity of chest symptoms. Therefore, routine screening for symptoms of anxiety and depression is a worthy endeavor, and those identified with elevated clinical symptoms should be referred to receive appropriate treatment.