Objective: To describe the oral health related knowledge, behaviour, and attitude towards health of 12-year old Lao schoolchildren; analyse how health risk factors relate to socio-demographic background; and determine the relative effect of living conditions on health and risk behaviour. Methods: Cross sectional study of 12-year old schoolchildren chosen by multistage sampling to fit the objective of the study. The final sample comprised 621 children of 2nd grade of secondary schools in Vientiane, Lao Peoples Democratic Republic. Data were collected by structured questionnaire covering behaviour, attitudes and knowledge related to oral and general health and perception of own health. Results: 69% of the children reported toothache during the previous 12 months and 38% reported school absenteeism due to toothache. Nevertheless, 77% stated frequent brushing and 91% the use of fluoridated toothpaste. Only 29% reported dental visits for this period while 42% had never seen a dentist. Fear of pain, cost and distance were stated as barriers for dental visits. Knowledge on caries prevention was high, aetiology of oral disease less known, and intake of hidden sugar surprisingly frequent. Socio-economic position and attitude towards health were important predictors for oral health behaviour and risk behaviour. Conclusions: Despite regular tooth brushing practice and widespread use of fluoridated toothpaste school absenteeism due to toothache is high. Significant socio-demographic gradient exists in risk factors for oral health. To reduce oral health inequality systematic oral health promotion should be implemented through the existing school health platform strengthening healthy behaviour and focussing on risk factors for oral as well as general health. Key words: Laos, oral health, behaviour, attitude, knowledge, children, school, absence, toothache, health promotion