The gold standard for assessing quality of forced expiratory manoeuvres is visual inspection by an expert. Numeric ATS/ERS quality criteria (NQC) include back extrapolated volume (BEV), repeatability and forced expiratory time (FET). Currently available equipment provides feedback tempting the investigator to use NQC as pass-fail-criteria.To investigate whether using NQC instead of visual acceptability is a valid option, we analysed data from a multi-centre national reference study in Germany of children 4 to 18 years old. Spirometry was performed under field conditions. ROC-analysis was used to assess performance of BEV, repeatability, FET and a combination thereof in relation to visual acceptability.We included data of 3133 healthy Caucasians in the analyses; 72% delivered at least two visually acceptable manoeuvres. Of these 59% would have been rejected based on combined NQC, mainly because the FET criterion was not feasible. Specificity of the NQC was generally low (BEV 10%, repeatability 30%, FET 50%). ROC-analysis showed that a combination of the three measures could reach at best a sensitivity of 90% and specificity of 56%.We conclude that visual control is mandatory, NQC may help obtain the best possible results, but a fixed cut-off for FET should be abandoned.