The aim of this study is to assess the prevalence of parafucntional oral habits including breathing disorder, bruxism, thumb-sucking, clenching and some of the related factors among a group of Saudi dental patients ranging from 6 to 16 years of age. The sample of this study comprised 1032 Saudi children (712 boys and 320 girls) collected from the screening clinic, Faculty of Dentistry, King Abdulaziz University. Standardized questionnaire form, information about the presence or absence of different parafunctional oral habits and the participant's oral health knowledge was obtained. Age, sex and number of siblings were collected. Descriptive statistics, t test and Chi square test were used as appropriate. The prevalence of breathing disorders, bruxism, thumb-sucking and clenching habits were 20.2%. 30.2%, 16.7% and 13.6%, respectively. Bruxism was more prevalent in boys (33.1%) than girls (23.7%), while girls had a significantly higher prevalence of thumb-sucking and clenching (p=0.001). The number of siblings had a significant effect on bruxism and thumb-sucking (p=0.04), but not on breathing disorder (p=0.44) or clenching (p=0.22). Oral health knowledge had insignificant effect on breathing disorders, bruxism, thumb-sucking and clenching (p=0.88, 0.71, 0.28 and 0.31, respectively).