Objective: To determine whether the use of acetylcysteine in children is supported by literature data and to determine how often and for what indications acetylcysteine is prescribed for children in general practice., Design: Systematic literature review and general practitioners audit., Setting: Academic Hospital Groningen, the Netherlands., Methods: A Medline search was performed and the references of the articles found were checked. All 720 general practitioners working in the three northern provinces of the Netherlands were mailed a questionnaire regarding their prescription of acetylcysteine for children., Results: Of the studies on acetylcysteine in children with pulmonary disorders (excluding cystic fibrosis) (n = 15) the majority (n = 12) were uncontrolled clinical observations. Three clinical trials were found, all of which showed considerable methodological shortcomings. The observed benefit of acetylcysteine therapy in these studies was of no clinical relevance. The questionnaire was filled out completely and returned by 70.3% of general practitioners. Almost one-third of the general practitioners (32.6%) prescribed acetylcysteine now and again for children with various pulmonary disorders (such as 'mucus that is difficult to bring up' (73.9%), asthmatic bronchitis (50.3). bronchitis (40.0%), excessive mucus production (40.0%) and dry cough (34.5%))., Conclusion: Acetylcysteine is being prescribed frequently for children with various pulmonary disorders by general practitioners whilst the use of this drug is not being supported by literature data.