Pneumonia on under-five children is define as one of the major pediatric health crisis, contribute to highest morbidity and mortality globally particularly in developing nations. In Eastern Indonesia, pneumonia on under-five children is mostly predicted by environmental factor such as children are exposed to household smoke and tobacco smoke. This is caused by the lack of information received and lack of awareness on the effect of secondhand smoke on under-five children with pneumonia. This study was aimed to explore the parents perception on the effect of tobacco smoke exposure on under-five children with pneumonia. This study was a qualitative study using fenomenology approach. The participants in this study were 11 parents of under-five children with pneumonia. The data collection conducted through in-depth interview then analyzed using Coalizzi method. The themes identified in this study were (1) parents views on the effect of tobacco smoke; (2) the effect of tobacco smoke on under-five children; and (3) the impact of tobacco smoke on family. These themes identified the perception of parents with under-five children with pneumonia in Manggarai that the under-five children in Manggarai were on high risk of tobacco smoke exposure on several occasions. Tobacco smoke would not only endangering childs health but also burdening familys social and economy well-being. The improvement of parental awareness on the effect of tobacco smoke needed to comprehensivelyfacilitated by nurses through effective educating communication that suited with familys needs and conditions.