Background: Diarrhea is a problem of health that often occurs in children. Untreated diarrhea can lead to death due to dehydration. Children experiencing diarrhea should be properly cared for to overcome dehydration and prevent its recurrence. Such abilities should be demonstrated by mothers who have children under five years. Discharge planning programs in hospitals can increase maternal knowledge and readiness in caring for children with diarrhea. Purpose: The purpose of this study was to determine the effectiveness of discharge planning programs on maternal self-efficacy in the prevention of diarrhea in children. Methods: This study used a pretest-posttest quasiexperimental design with a control group. The samples were 60 mothers of children aged 0-5 years old undergoing treatment in the hospital due to diarrhea. The samples were randomly recruited and assigned to the intervention group (n=30) that received discharge planning programs during treatment and the control group (n=30) that received health education based on hospital standards. The data were collected using the Self-Efficacy Scale for Preventing Early Childhood Diarrhea and analyzed using the independent ttest. Results: Results of the study indicated that discharge planning programs were effective in increasing maternal selfefficacy in the prevention of diarrhea with a p-value of 0.000 and a mean difference of 29.533. After the intervention, the mean score of maternal self-efficacy in the intervention group and the control group was 106.60 (high) and 77.7 (moderate), respectively. Conclusion: Discharge planning programs could increase maternal self-efficacy in the prevention of diarrhea. Structured discharge planning programs can provide ease for mothers to receive the information needed during the treatment.