SUMMARY Introduction: Socioeconomic impact and mortality caused by acute diarrheal disease (ADD) has been a concern of international organizations. One solution is to promote education in the population at risk. ADD prevention basic strategies include measures such as hand washing, food hygiene, proper disposal of excreta and vaccination. Objective: To determine maternal knowledge in primary strategies for preventing diarrhea. Methods: This is a cross-sectional observational survey study that included mothers attending pediatric services at the Instituto Autonomo Hospital Universitario de Los Andes, November - March 2012. Pearson Chi-square was utilized (p < 0,05) for statistical analysis. Results: 111 mothers were included, 50.4% were between 20 - 35 years of age; 40.6% were from the sanitary district of Merida and were classified as social strata Graffar IV-V; 33.3% had high school education. However, only 14.4% had adequate knowledge in regard to strategies in primary prevention in diarrhea, with lack of knowledge in 85% of the availability of the vaccine anti-rotavirus. Only 28% had employed oral hydration solutions. A significant association between low maternal education level and socioeconomic level with poor knowledge in prevention in ADD was found (p = 0.002). Conclusions: Lack of maternal knowledge of prevention in ADD strategies is in direct relation with low level of maternal education and socio-economic level, which emphasizes the importance of educational campaigns directed to these groups. Food, oral rehydration and vaccines are topics to reinforce. Sanitation and promoting hygiene with community participation may lead to a significant reduction of the incidence of diarrhea in children.