In children with chronic renal failure (CRF) anorexia, nausea, and vomiting are common yet poorly understood symptoms. We studied oesophageal and gastric motor function in 12 children (age 7 months-6.8 years) with severe CRF not undergoing dialysis who had persistent anorexia and vomiting. Eight of 12 patients had significant gastro-oesophageal reflux (reflux index 5.2% to 21.9%, mean 11.3%; controls < 5%), 7/10 had altered gastric half emptying times (T1/2) for 5% glucose or milk (glucose meal--controls: 8-14 min, two CRF patients: 18-25 min; milk meal--controls: 48-72 min, five CRF patients 27, 28, 82, 83, and 110 min). Gastric antral electrical control activity was abnormal in 6/11 patients, with different types of gastric dysrhythmias whereas the remainder and controls showed a regular dominant frequency of 0.05 Hz. In 7/9 patients fasting serum gastrin concentration was raised (53 to > 400, mean 168 pmol/l, controls < 40 pmol/l). All CRF patients with anorexia and vomiting had one or more disorder of foregut motility. The nature and variety of the motor disorders and the raised concentrations of circulating gastrin suggest that the normal environment generated by CRF affects the function of the smooth muscle of the foregut.