Three cases of gastroduodenal perforation and one case of ulceration and extreme thinning of the gastric wall occurred in preterm babies treated with dexamethasone for bronchopulmonary dysplasia. This complication of treatment with steroids has not to our knowledge previously been described in preterm infants. Urgent abdominal paracentesis was an essential part of the resuscitation in these cases, and this potentially serious side effect should be considered in all babies treated with steroids.