Objective: To evaluate the effect of using an educational booklet combined with a brief motivational interview on maternal self-efficacy in preventing childhood diarrhea. Materials and Methods: Quasi-experimental study carried out with 35 mothers. For data collection, the Maternal Self-Efficacy Scale for the Prevention of Childhood Diarrhea (EAPDI, em português) was applied, and later an educational intervention based on the application of the booklet “You are able to prevent diarrhea in your child!” associated with a brief motivational interview. One month after the intervention, the EAPDI and a form to verify the occurrence of diarrhea were applied by telephone. For data analysis, statistical tests were applied. The study was approved by the Research Ethics Committee. Results: There was an increase in maternal self-efficacy scores in preventing childhood diarrhea throughout the study (p< 0.001), a progressive increase in the number of mothers who showed high self-efficacy (p< 0.001) and a decrease in the occurrence of cases of diarrhea one month after the intervention (p= 0.021). Conclusions: The educational intervention helped to increase maternal self-efficacy in preventingchildhood diarrhea and to reduce diarrheal episodes in children, also proving to be an instrument capable ofincreasing the autonomy of mothers in caring for their children.Objetivo: Evaluar el efecto del uso de una cartilla educativa combinada con una breve entrevista motivacionalsobre la autoeficacia materna en la prevención de la diarrea infantil. Material y Método: Estudio cuasiexperimental realizado con 35 madres. Para la recolección de datos se aplicó la Escala de Autoeficacia Materna para la Prevención de la Diarrea Infantil (EAPDI), y posteriormente una intervención educativa basada en la aplicacióndel cuadernillo “¡Tú eres capaz de prevenir la diarrea en tu hijo!” asociada a una breve entrevista motivacional. Un mes después de la intervención, mediante contacto telefónico, se aplicó la EAPDI y un formulario para verificarla ocurrencia de diarrea. Para el análisis de los datos se aplicaron pruebas estadísticas. El estudio fue aprobado por el Comité de Ética en Investigación. Resultados: Hubo un aumento en los puntajes de autoeficacia materna en la prevención de la diarrea infantil a lo largo del estudio (p< 0,001), un aumento progresivo en el número de madres que mostraron alta autoeficacia (p< 0,001) y una disminución en la ocurrencia de casos de diarrea almes de la intervención (p= 0,021). Conclusiones: La intervención educativa ayudó a aumentar la autoeficacia materna en la prevención de la diarrea infantil y a reducir los episodios diarreicos en los niños, demostrando Objective: To evaluate the effect of using an educational booklet combined with a brief motivational interview on maternal self-efficacy in preventing childhood diarrhea. Methods: Quasi-experimental study, carried out with 35 mothers. For data collection, the Maternal Self-Efficacy Scale for the Prevention of Childhood Diarrhea (EAPDI) was applied, and later an educational intervention based on the application of the booklet “You are able to prevent diarrhea in your child!” associated with a brief motivational interview. One month after the intervention, by telephone contact, the EAPDI and a form to verify the occurrence of diarrhea were applied. For data analysis, statistical tests were applied. The study was approved by the Research Ethics Committee. Results:Houve aumento dos escores de autoeficácia materna em prevenir a diarreia infantil ao longo do estudo (p<0,001), aumento progressivo do número de mães que apresentaram alta autoeficácia (p<0,001) e diminuição da ocorrência de casos de diarreia um mês após a intervenção (p=0,021). Conclusões: A intervenção educativa ajudou a aumentar a autoeficácia materna na prevenção da diarreia infantil e na redução dos episódios de diarreia nas crianças, revelando-se também um instrumento capaz de aumentar a autonomia das mães no cuidado das crianças.