Congenital Glucose Galactose malabsorption (CGGM) is a rare disorder with limited data from the Arab world. We report the first case of CGGM in Oman. B.S.A two years old female who presented with chronic osmotic diarrhea since birth with hypernatraemic dehydration. B.S was found to have Glucose Galactose Malabsorption based on clinical trial of ORS and elemental formula. Symptoms resolved on introduction of Carbohydrate free formula. The patient developed many complications while on TPN including rickets and nephrogenic diabetes insipidus. These complications have not been reported earlier in CGGM.