Diarrhea is still one of the leading causes of morbidity and mortality in almost all geographic areas of the world and all age groups can be attacked by diarrhea, but severe disease with high mortality especially occurs in infants and toddlers. The study aims to determine whether there is a relationship between environmental and sociodemographic factors with the incidence of diarrhea in toddlers in Karang Anyer Village, Secanggang District, Langkat Regency. This type of research is descriptive correlation where descriptive correlation is with a cross-sectional approach, the population is all children under five as many as 35 people, data collection was carried out for 1 month by sampling with the Total Sampling method. data collected using questionnaires, data analysis used is bivariate. The results showed that based on the analysis of the spearman test, obtained a value of 0.525 the better the environment is expected the incidence of diarrhea in toddlers does not exist and there is a relationship between the environment and the incidence of diarrhea with a p value = 0.001, there is a relationship between the environment and the incidence of diarrhea with a p value = 0.001, there is a sociodemographic relationship with the incidence of diarrhea with a p value = 0.000.