Lower respiratory tract infections in children with severe neurodisability are usually caused by aspiration of stomach contents from gastroesophageal reflux (GOR) or direct aspiration (DA) of food due to oral and pharyngeal motor problems. To determine the contributions and interactions of GOR and DA, oesophageal 24-hour pH monitoring and feeding videofluoroscopy were performed in 34 children (age range 7 months to 16 years, mean 7 years) who had severe physical and learning disabilities and who were slow feeders. Subjects were divided into three groups according to the frequency of their respiratory tract infections. Subjects in group 1 had no respiratory tract infections (N=10); five had GOR and none had DA. Subjects in group 2 had minor respiratory tract infections but had not received more than one course of antibiotics for this in the previous year (N=8); two had GOR alone, four had DA alone, and two had neither. All subjects in group 3 had recurrent respiratory tract infections (N=16); one had GOR alone, seven had DA alone, and eight had both GOR and DA. This study suggests that oral and pharyngeal motor problems are the major cause of respiratory tract infection in children with severe neurodisability. These problems lead to DA and, if GOR is present, to the aspiration of stomach contents. Those children with both DA and GOR are more likely to have severe respiratory tract infections which may lead to gastrostomy feeding (together with fundoplication). GOR without sufficient oral and pharyngeal motor problems to cause DA is less likely to cause respiratory tract infection in children with severe neurodisability.