In a study, partly retrospective and partly prospective, there were 29 infants who had sliding hiatal hernia: their principal clinical features, the diagnostic criteria, treatment and cure rate were similar to those of other series. The study highlights associated duodenal anomalies which seem to influence the radiological but not the clinical cure rate. The findings can be contrasted with those in adults who have duodenal abnormalities with sliding hiatal hernias in that 21 out of 29 infants with sliding hiatal hernia had a normal duodenal loop. Severe dyspepsia, with malnutrition initially, did not have any influence on physical development in 27 out of 29 patients.