A culture from the lower airway secretions is the optimal sample to guide antibiotic therapy in cystic fibrosis (CF) lung disease. The authors therefore examined whether sputum induction is an efficient, safe and acceptable procedure in CF children without spontaneous expectorations. Nineteen patients were studied. Their mean age (range) was 8.6 yrs (4.3-15.2 yrs). Their mean forced expiratory volume in one second (FEV1) was 88% predicted (46-122%). NaCl solutions from 0.9-6% were inhaled, after baseline lung function tests before and after salbutamol. All patients did produce secretions. Alveolar macrophages were present in 16/19 induced samples. The procedure induced minor but significant bronchoconstriction: the mean change (range) in postsalbutamol FEV1 (% pred) was -7 (-24-16). Percutaneous oxygen saturation remained above 90% in all children. The test had to be discontinued in one child because of cough and wheeze. Acceptability of the procedure evaluated using a visual analogue scale from -7-7 showed a mean value (range) at the final concentration of -1.23 (-6.16-5.88). It is concluded that sputum induction is possible, safe and acceptable in cystic fibrosis children who do not expectorate spontaneously.