Background: ARI (Acute Respiratory Infections) are the biggest cause of mortality in toddler in Indonesia. In 2018, there were 12,842 toddler in Tangerang. Interviews found that 48% of toddlers that went to health centers in Tangerang’s Kelapa Dua district between January and February 2020 had ARI. Research objectives: To obtain an overview of parents’ knowledge and behaviours regarding ARI in toddler. Research methods: This research uses descriptive quantitative methods. The population is parents who have toddler in the Kelapa Dua district. 180 samples were taken using the total sampling technique. The research instrument used was a questionnaire from Bidaya, Ligita, and Trissya (2012) which has been tested for validity and reliability (Cronbach's Alpha - questionnaire on parents’ knowledge: 0,761; questionnaire on parents’ behaviour: 0,746). Results: Based on univariate test results, 94 respondents (52.2%) had a high degree of knowledge about ARIs in toddler, and 131 respondents (72.8%) had good behaviours regarding ARIs in toddler. Recommendation: For further research can develop regarding the factors that influence the knowledge and behavior of parents of ARI in toddler.