A randomized pilot study was carried out to compare the safety and effectiveness of rice powder salt solution (RPSS) in combination with milk-rice mixture (RPSS-MR group, n = 17) with other two regimens, glucose-based oral rehydration solution (ORS) combined with MR (ORS-MR group, n = 17) and ORS combined with formula milk (ORS-milk group, n = 14) in the treatment of acute watery diarrhea with mild to moderate dehydration in 48 boys younger than 2 years. Results showed that in the first 24 hours patients in the RPSS-MR group had significantly smaller amounts of stool weight (32.7 g/kg) than those in the ORS-MR group (67.5 g/kg) and ORS- milk group (59.2 g/kg) (p< 0.05 for both measurements). Patients in the RPSSMR group also had significantly shorter duration of diarrhea (29.6 hours) than the other two groups (43.8 hours and 49.6 hours, respectively) (p < 0.05 for both measurements). The stool weight and duration of diarrhea between the ORS-MR group and the ORS-milk group were not significantly different. The positive effect of milk rice mixture was not demonstrated in the study due to the significantly more severe diarrhea in the ORSMR group. The effectiveness of the RPSS-MR is therefore likely due to mainly RPSS.