The experience of 1 year of home intravenous antibiotic treatment of patients with cystic fibrosis is reported. Ninety-two courses were given to 31 patients, aged 4-67 years (mean age, 21 years). All patients improved clinically and biochemically. The mean weight gain was significant (p less than 0.001). Blood PO2 increased significantly (p less than 0.01), and the forced expiratory volume in 1 sec in percentage of predicted values also improved significantly (p less than 0.001). The patients could attend school and work and wanted to have the same kind of home treatment at the next subclinical exacerbation. The possibility of avoiding hospitalization improved social life and made the patients feel responsible and therefore were cooperative with treatment before clinical deterioration.