Sandifer's syndrome is a rare manifestation of gastroesophageal reflux (GER) in children, occurring in association with abnormal movements of the head, neck, and upper part of the trunk. Out of 65 children with Sandifer's syndrome described in literature, only 2 were breast-fed. We report on a 15-day-old breast-fed girl affected by Sandifer's syndrome. Pathological GER was diagnosed with 24 h pH esophageal monitoring. In our patient, all the symptoms of Sandifer's syndrome disappeared when she was cow's milk formula-fed. The role of food allergy to dietary proteins ingested by a lactating mother is discussed.