BACKGROUND AND AIM: Refractory constipation is an extremely common problem in infants and children. The diagnostic suspicion of Hirschsprung disease often arises in this clinical setting. Diagnosing Hirschsprung disease can be difficult; however, excluding the diagnosis is much easier, only requiring the demonstration of ganglion cells in the distal rectum. The most common method for obtaining tissue from the rectum involves a blind suction biopsy. This technique has been complicated by serious adverse events, equipment malfunction, and inadequate specimens. Our goal was to evaluate the adequacy of specimens obtained with a flexible endoscope and jumbo biopsy forceps to rule out Hirschsprung disease in the child outside the newborn period. PATIENTS AND METHODS: We retrospectively reviewed 668 rectal biopsies taken during 167 endoscopies on 156 patients being evaluated for Hirschsprung disease from 2001 to 2008 at the Baystate Medical Center Children's Hospital. Four biopsies were taken from each patient approximately 2.5 cm from the anal verge. Biopsies were obtained using a flexible endoscope and jumbo biopsy forceps. During the first 6 years the Olympus FB-50U-1 large cup fenestrated biopsy forceps was used. During the last 2 years the Boston Scientific Radial Jaw 4 Jumbo biopsy forceps was used instead. RESULTS: The Boston Scientific Radial Jaw 4 Jumbo biopsy forceps yielded adequate specimens 93% of the time, which surpassed most published results of other techniques. There were no complications reported. CONCLUSIONS: Obtaining rectal biopsies with a flexible endoscope and jumbo biopsy forceps is a safe and effective means to rule out the diagnosis of Hirschsprung disease in children.