Purpose: This study aimed to identify the correlation between cough etiquette knowledge and practice levels of mothers with preschooler and the practice level of cough etiquette with children perceived by their mothers. Methods: The data were collected by 160 mothers with preschoolers attending two daycare centers and three kindergartens in G city, South Korea from February to March 2018 by using self-reported questionnaires. Results: The correct answer rate of cough etiquette knowledge level in mothers was averaged of 10.32±1.79 out of 12 (86.0%) and practice level was averaged of 33.65±4.14 out of 48 (70.1%). Their children’s practice level was averaged of 28.39±4.85 out of 48 (59.1%). The correlation between cough etiquette knowlege and practice levels of mothers were not stastically significant. However, the level of children’s cough etiquette practice was positively correlated with mother’s cough etiquette level (r = .35, p < .001). Conclusion: The cough etiquette knowledge level with mothers did not reflect to their cough etiquette practice level. However, the higher the rate of cough etiquette practice level in mothers, the higher their children cough etiquette practice level. Development of systematic cough etiquette program for both mothers and children according to their developmental stages is essential to prevent from droplet-transmitted respiratory infection and to promote correct cough etiquette practice by making a habit of practicing it.