BACKGROUND: Gastroesophageal reflux disease (GERD) has a prevalence of 10% to 20% in the pediatric population. The 24-hour pHmetry is still considered the "gold standard" for its correct diagnosis. Omeprazole is the elective drug for a proper treatment. However, there are no adequate pharmaceutical presentation forms for infants. OBJECTIVE: To assess the acid suppression capacity of a new pharmaceutical association of omeprazole with sodium bicarbonate and sodium alginate (OBA), powder for oral suspension, in small infants with GERD. The response was measured according to the gastric variations of pH after a 3-day treatment with OBA. PATIENTS AND METHOD: This is a pilot, prospective, open study in infants with no congenital nor associated anomalies under 12 months of age with GERD. Two double channel pHmetry with gastric sensor were performed on different days in the same patient. The first one to establish the diagnosis (day 0) and the second one (day 3) after receiving omeprazole (OBA) at 1.5 mg/kg/day in a twice/dose/day (BID). RESULTS: The comparison between the frst and the second gastric pHmetry showed a statistically significant reduction in gastric acidity. No adverse events were observed in infants and the suspension flavor was palatable. CONCLUSIONS: This new presentation of omeprazole (OBA) with sodium bicarbonate and sodium alginate powder for oral suspension is capable of a significant and intense acid suppression, necessary for treatment of infants with GERD. The taste of the solution was well accepted by all the babies, which is a very important finding for this age group.