Introduction: Gastroesophageal reflux (GER) and cow's milk allergy (CMA) are the most common causes of persistent vomiting in infants and the two can be difficult to distinguish on clinical ground apart from the response to dietary antigen exclusion.Aim of the Work: Is to determine the incidence of gastroesophageal reflux (GER) and cow's milk allergy (CMA) in cases of persistent vomiting in Egyptian children.Methodology: This study include 30 patients, from those attending the outpatient clinic of About El Resh Hospital, complaining of persistent vomiting.Results: The incidence of cow's milk allergy (CMA) in cases of persistent vomiting was 43.3%.Conclusion: Gastroesophageal reflux (GER) is not only cow milk allergy-associated but also cow milk allergy induced.