Pulmonary insufficiency is the main cause of death in cystic fibrosis (CF). We analysed forced expiratory volume in 1 s (FEV1) data of 14 732 patients registered in the European Cystic Fibrosis Society Patient Registry (ECFSPR) database in 2007. We used linear and logistic regressions to investigate associations between FEV1 % predicted and clinical outcomes.