Background: Acute Respiratory Infection (ARI) is the biggest cause of death in the world, where WHO Global Fact noted there are 13 million children under five die each year and most of them occur in developing countries. In Indonesia, cases of death caused by ARI occupy the number one position with a number of 32.10%. Based on data obtained from the Dadap Posyandu, Tangerang, there are around 28 out of 32 toddlers who come to health services infected with ARI. Objective: To find out the description of mothers' knowledge and attitudes about ISPA towards Toddlers in Posyandu Dadap. Method: This research uses a quantitative method with a descriptive approach. The population in this study are mothers who actively participate in Posyandu activities and have toddlers who have had ARI. The sample in this study amounted to 32 mothers. This research was conducted in April to May 2020. Data analysis technique used was univariate analysis with non-probability data collection techniques, namely total sampling with instruments using an online questionnaire adopted from the property of Aderita Novia, 2008 "Knowledge and Attitudes of Mothers Toward ARI Prevention". Research Results: Mothers in Posyandu Dadap Tangerang have an average level of knowledge from sufficient to good with the same number of respondents, as many as 14 respondents (45.2%) for sufficient knowledge and good knowledge. Mothers in Posyandu Dadap also have an average positive attitude towards the prevention of ARI with a total of 16 respondents (51.6%) who have a positive attitude. Suggestion: For Posyandu for an educational plan about ARI prevention in children under five, for the next research can examine other factors that influence ARI prevention such as the environment and health workers