Aim: the study aims to observe the response to treatment with ORS only or ORS + gelatin tannate in two cohorts of pediatric patients with acute diarrhea, with the primary efficacy endpoint being the number of stools at 12 hours from baseline.Methods: children aged 3 months to 12 years were included in the study. Only children with acute diarrhea, more than 3 liquid stools, and duration inferior to 72 h were included. Number of stools was recorded as absolute number, categorized as ≤ 3 and ≥ 4 stools over 12 hours, and as a stool decrease index (SDI). Other clinical variables were recorded, including weight, fever, vomiting, stool characteristics, and signs of peritonitis/sepsis.Results: baseline characteristics for the two populations included a mean age of 2.3 years in the ORS group and 2.6 years in the ORS + gelatin tannate group. Children younger than 2 years represented 59.8 and 54.3% in the ORS and ORS + gelatin tannate groups, respectively. Clinical variables such as vomiting, dehydration, weigth, and stool decrease index were used to compare the two groups. We found a statistical significant difference between the two groups (p < 0.0001) --SDI for the ORS group was -0.1894; for the ORS + gelatin tannate group was -0.6023.Conclusions: we observed a significant decrease in the number of stools and an improvement in the consistency of stools in the ORS + gelatin tannate group. Other clinical variables such as vomiting, dehydration, weight, bloody stools, and peritonitis/sepsis signs showed no statistical differences between the two groups, but did show a general trend toward improvement. The Stool Decrease Index (SDI) showed a 18% decrease in the number of stools for the ORS group and 60% for the ORS + gelatin tannate group. The use of ORS + gelatin tannate was associated with a greater decrease in SDI. Gelatin tannate decreased the number of stools at twelve hours in children.