The authors report a successful Meckel's scan performed 26 hours after a labeled RBC study using a commercial in-vitro labeling kit, UltraTag (Mallinckrodt Medical, Inc., St. Louis, MO). No abnormal alteration of Tc-99m distribution was observed as would be seen if an in-vivo RBC labeling technique was used. This case demonstrates that it is feasible to perform an in-vitro labeled RBC study for acute gastrointestinal bleeding in pediatric patients and to follow-up with a Meckel's scan if it is necessary for diagnostic confirmation.