G Giardiasis is a diarrheal disease caused by the pathogenic protozoa Giardia lamblia. The highest incidence of diarrhea based on age group occurred in underfives. Urbanslum areas are one of the areas that have a highest risk of diarrheal disease. This isdue to a lack of environmental sanitation and population hygiene. This researchaims to determine whether there is a relationship of Giardia lamblia infection and environmental sanitation with incidence of diarrhea in underfives (Examination OfCases Of Non-Hemorrhagic And Non-Mucous Diarrhea). This research uses an observational analytic with cross sectional design that includes 60 under fives who came to the Jatinegara District Health Center. Data was collected by interview using questionnaires on the incidence of diarrhea and environmental sanitation. Giardia lamblia infection is done by examining stool directly. The data was analyzed by SPSS version 25 with significance level of 0,05. The result of univariate data analysis showed that the average sex of male under fives with under fives aged between 1-15 months and the nutritional status of normal under fives. The factors cause diarrhea showed that the average are Giardialamblia infections, protected drinking water sources, the physical quality of clean water does not meet the requirements, does not have latrines and the type of waterproof house floor. The results of bivariate data analysis using Fisher's Exact Test showed the relationship of Giardia lamblia infection with incidence of diarrhea in under fives with p value 0,001. The relationship of environmental sanitation with incidence of diarrhea in under fives with p value 0,002. From the research that have been done, it can be concluded that there is a significant relationship between Giardia lamblia infection and environmental sanitation with incidence of diarrhea in under fives (Examination Of Cases Of Non-Hemorrhagic And Non-Mucous Diarrhea).