Exposure to secondhand smoke can lead to various diseases and developmental defects among people and, more specifically, children, which this thesis is based on. The findings of this thesis confirmed that there is a significant relationship between involuntary smoking on children’s oral health who are exposed to this issue and the development of oral diseases and defects that can affect dental hard tissues, periodontal soft and hard tissue structures, soft tissues in the oral cavity such as gingiva and mucosa, salivary gland function and flow rate of saliva, as well as the creation of oral-facial clefts. So it can be concluded that indeed repeated exposure of a child to secondhand smoke exerts negative effects on the child’s oral health which can cause several problems in the future.