The Standardisation Committee of the European Cystic Fibrosis Society Clinical Trial Network has undertaken the evaluation of clinical end-points for therapeutic interventions regarding their use in multicentre clinical trials in cystic fibrosis (CF). This review of biomarkers in bronchoalveolar lavage (BAL) is part of the group's work. The aims of this project were: 1) to review the literature on reliability, validity and responsiveness of BAL in patients with CF; 2) to gain consensus of the group on the feasibility of BAL; and 3) to gain consensus on answers to key questions regarding the promotion of BAL to surrogate end-point status. Assessment of BAL inflammatory markers in the literature indicates that their reliability, validity and responsiveness are adequate for clinical trials. After discussion of the practical characteristics it was concluded that BAL has an attractive validity profile, albeit with limited feasibility. It is particularly applicable to multicentre trials in preschool children with CF and early or mild lung disease. This is the first article to collate the literature in this manner. This provides a rationale to support the use of BAL in early clinical trials in preschool children with CF.