Recently four of 38 children with a kidney transplant were diagnosed with bronchiectasis. The aim of the current study was to identify patients with increased risk for pulmonary damage. In this cross-sectional observational study, children with a functioning kidney graft in the Netherlands and Antwerp, Belgium, were screened with the use of a symptom checklist and spirometry. Maximum score for upper airway complaints was 21 (normal: <8), for lower airway complaints 28 (<10). Results of FVC, FEV(1) and MEF(25) were expressed as percentage predicted for height and sex. One hundred and thirty-five patients completed the interview (122) and/or spirometry (103); 91 did both. Lower airways symptoms were above acceptable levels in 18 (14%) patients. Forty-nine patients (48%) had an abnormal lung function test: in 12 concerning FVC%, in 11 FEV(1)%, in 24 MEF(25)% and in 36 FEV(1)/FVC. Of correlations between symptomatology or spirometry data, and clinical parameters, only that between GFR and MEF(25)% was statistically significant. Children with a kidney transplant are at increased risk for obstructive lung disease. We recommend to monitor lung function during the follow-up after renal transplantation.