The cases are reported of five children with chronic renal failure who underwent gastrocystoplasty for a variety of urological disorders. Gastrocystoplasty comprises the transplantation of a vascularised segment of stomach to the bladder to form an augmented neobladder. The patients had gastrointestinal complications after the operation, including considerable weight loss in all five patients, accompanied by marked failure to thrive in four of the five patients, and food aversion, feeding intolerance, dumping syndrome, delayed gastric emptying, and oesophagitis in two patients. Three of the five patients developed severe abdominal pain and haemorrhagic cystitis secondary to gastric acid secretion in the neobladder from the transplanted gastric pedicle. Nutritional and pharmacological interventions were used to manage the gastrointestinal problems. Explanations are offered for the pathophysiology of the observed complications of gastrocystoplasty. It is believed that the use of this procedure in infants and children, particularly those with chronic renal failure and uraemia, warrants caution until successful long term follow up and experience with this procedure have been reported.