Gastro-oesophageal reflux (GOR) was studied by continuous 1 h recording and 4 h pictures after a 99Tcm-labelled sulphocolloid meal in 57 children. The GOR rate Re, pulmonary aspiration rate A and 60 min gastric emptying GE were calculated as a percentage of the initial activity G0. GOR was visualized in 46 children (Re mean value = 1.54%); pulmonary aspiration was detected in 13 children (A mean value = 0.09%). Higher Re values were correlated with positive barium studies (Re mean value = 1.84% versus 0.61% in negative barium studies), and with slower gastric emptying (GE = 27.6% in children with an Re higher than 3% versus 44.2% in children with an Re lower than 1% P < 0.01). Pulmonary aspiration was correlated with low gastric emptying (GE = 28.4%). Late 4 h reflux is better correlated to oesophagitis than to pulmonary aspiration. These results show the role of gastric dysmotility in reflux genesis and suggest that reflux time could be of predictive value in oesophagitis risk in children with GOR. Early postprandial and short gastro-oesophageal reflux is physiological. Fasting, iterative and persistent reflux results in a pathological condition with the risk of pulmonary aspiration and oesophagitis.