Health promotion aims to ensure that the population has improved living and health conditions, and schools are appropriate environments in which to do this. The purpose of this study was to investigate the impact of health promotion in terms of oral health in special schools for mentally disable pupils in Brazil. The study was cross-sectional and adopted a qualitative and quantitative approach, using triangulation methods to observe the reality. An epidemiological survey was performed in order to analyse the oral health status; a semi-structured questionnaire and participative observation were used for the qualitative analysis of the health promotion activities undertaken in the schools; case studies were carried out to evaluate the profile of oral health status in the context of the schools. The sample was comprised of 383 school-children aged 2-19, stratified among 7 schools, Curitiba/Paraná/Brazil. The analysis was performed by means of frequency distribution and associations between variables, using the SPSS 16.0 program. The oral health status prevalences in the population studied were dental caries, 49.3%; bleeding gums, 23.8%; dental trauma, 11% and toothache in the last 3 months, 17,8%. Dental caries and bleeding gums experience was associated with the level of the mother's education (p<0.00) and age group (p<0.00). Dental trauma and toothache in the last 3 months were associated with the level of the mother's education (p<0.00 and p<0.00, respectively). Analysis of the dimensions of health promotion demonstrated that health is being promoted in all the schools studied. However, the analysis of oral health indicators per school revealed a possible interference of socio-demographic aspects in the results. It was concluded that the analysed special schools for the mentally disabled promote health. However, the socio-demographic profile of this population appears to have greater influence on vulnerability than the school context in relation to oral health status.