BACKGROUND AND AIM: : Scintigraphic gastric emptying study (GES) is the criterion standard for diagnosis of gastroparesis. Adult studies demonstrated that extending GES to 4 hours increases its ability to diagnose delayed gastric emptying. Most pediatric centers assess GES up to 2 hours postmeal. The aim of the present study was to assess the effect of extending GES from 2 to 4 hours in evaluation of children with suspected gastroparesis. METHODS: : We conducted a chart review of all children who had a 4-hour GES with standard radiolabeled solid meal in 2009-2010. Results of GES at 1, 2, and 4 hours were compared. Patients were diagnosed as having gastroparesis using adult criteria: if gastric retention of meal was >90%, 60%, and 10% at 1, 2 and 4 hours, respectively. A telephone survey assessed GES time at top 20 pediatric gastroenterology centers in the United States. Cost of evaluation of patients diagnosed as having gastroparesis was estimated. Full-time equivalents of nuclear medicine technicians and number of nuclear medicine studies done at Ann & Robert H. Lurie Children's Hospital of Chicago from 2007 to 2010 were examined. RESULTS: : A total of 71 patients (32 boys, average age 10.8 years) were studied. Sixty-two percent (n = 44) children had abnormal GES; 23% (8/35) of them who had normal values at 2 hours had abnormal GES at 4 hours (P < 0.0001). Twenty-eight percent of patients had delayed GES at 1 hour: all persisted to have abnormal GES at 2 and 4 hours. Cost of evaluation of a child for gastroparesis was $9014. Only 5 of the top 20 pediatric gastroenterology centers in the United States conducted 4-hour GES. Transitioning from 2 hours to 4 hours only required scheduling adjustments and did not result in limitation in the number of scheduled patients. CONCLUSIONS: : Extending GES to 4 hours results in a considerable increase in diagnosis of gastroparesis.