Three hundred and sixteen patients with cystic fibrosis were seen at the Brompton Hospital during 1965-83; 178 (56.3%) of them were male and 136 female, and their ages ranged from 12 to 51 years. Most patients presented in infancy with respiratory symptoms and malabsorption, but 19 (6%) were diagnosed in adult life, three in their 30s. Pulmonary disease was almost universal (99.7%), being responsible for 97% of all deaths and three quarters of hospital admissions. All patients had developed a productive cough by the age of 21 and over half before the age of 5. Many complained of wheezing, but reversible airflow obstruction was present in only 40% of those tested. Minor haemoptysis was very common (62%), but major episodes less so (10%). Pneumothorax was seen in 61 cases (19%), and was often recurrent. Some irreversible airflow obstruction was present in all patients with pulmonary disease. Two patients have been followed for over 20 years without showing appreciable decline in lung function. Thirty five patients (11%) had no symptoms of malabsorption. Acute meconium ileus equivalent was seen in 16% and a chronic partial obstruction with episodic symptoms in a further 19%. Diabetes mellitus developed in 36 patients, 13 of whom were insulin dependent. Hepatomegaly was common (29%), often occurring without abnormal results in biochemical tests of liver function; only 1% of patients developed portal hypertension with varices and ascites. Skin reactions to at least one common allergen, including Aspergillus fumigatus, were positive in 70%, but very few patients suffered from hay fever or eczema. One hundred and twenty one patients have died, 97% from infection or other pulmonary complications, and 195 were alive in December 1983 (mean age 23 years). Seventy eight per cent of patients were in full time education or full or part time employment, or were housewives, and only 41 were unemployed for reasons for health. Many patients are married and 10 women have borne children. Most patients were admitted to hospital only three or four times during the period of follow up and 50 individuals (16%) have never been in hospital at all. The improvement in prognosis and quality of life for adults with cystic fibrosis should encourage a positive attitude in those who care for them.