In macroamylasemia, a macromolecular complex consisting of amylase linked to immunoglobulins circulates in the plasma and usually causes benign hyperamylasemia with low or normal amylasuria. Macroamylasemia is extremely rare in pediatric patients as it has been described in only four patients. We report herein the case of a 5-year-old girl with abdominal pain and macroamylasemia. To recognize macroamylase, we used agar gel electrophoresis, PEG precipitation, and fast protein liquid chromatography (FPLC). In our case, FPLC was found to be the most reliable method for the identification of the macromolecular complex. Macroamylasemia is merely a biochemical abnormality that is not associated with any kind of pathology. Its identification is therefore essential in order to avoid a wrong diagnosis, i.e., pancreatitis, with consequent inappropriate therapies.