Due to the frequent presence of latent gastroesophageal reflux (GER) in mentally impaired children, it is now standard to perform upper gastrointestinal contrast (UGI) and pH probe studies in all children referred for feeding gastrostomy, even if they are without clinical evidence for GER. For patients with documented GER, an antireflux operation performed in conjunction with gastrostomy is usually considered mandatory. Some authors have suggested that a "protective" antireflux operation be performed at the time of gastrostomy placement in all brain-damaged children, citing a high incidence of postoperative GER in this group of patients following gastrostomy, even with a negative preoperative evaluation for GER. To evaluate this theory, we prospectively studied, over the past 6 years, all mentally retarded children referred for feeding gastrostomy with UGI contrast and esophageal pH probe studies. In total, 148 children were studied; 105 had a positive evaluation for GER and underwent gastrostomy and antireflux surgery. Of the 43 children with a negative preoperative evaluation for GER, 37 are doing well following gastrostomy alone without clinical reflux at an average follow-up of 21 months. Six of the 43 (14%) developed symptomatic GER occurring at an average of 10 months following gastrostomy placement. Five of these children have been successfully treated with an antireflux operation and the sixth patient has been successfully managed nonoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)