OBJECTIVE The aim of the present study was to investigate the distribution of oral cariogenic bacteria among 12-year-old Palestinian children attending schools in East Jerusalem. METHODS Salivary levels of mutans streptococci (MS) and Lactobacilli (LB) were examined by semi-quantitative commercial kits and then correlated to social-demographic parameters. RESULTS Overall, 52.1 % of the examined children presented the highest possible ranking score categories for MS bacteria, with only 5.4 % in the lowest category. Only 12.6 % of the school children presented the highest LB score, while 25 % had the lowest ranking score. Salivary MS levels in children attending private schools were lower than those of children in government schools and United Nations Relief and Works Agency (UNRWA) schools. Conversely, levels of LB were lowest in children attending UNRWA schools compared to government and private schools. Girls had significantly higher amounts of MS and LB than boys (p = 0.001). Lower MS levels were significantly related to the following socioeconomic variables: higher father's education level (p = 0.037), higher mother's education level (p = 0.063), mother's employment status (p = 0.012), and lower home density (p = 0.001). For LB, the only significant socioeconomic variable was higher father's employment level, which was related to lower LB level (p = 0.025). CONCLUSIONS Levels of MS and LB were found to be strongly related with socioeconomic status among Palestinian children in East Jerusalem. The relatively high prevalence of cariogenic bacteria suggests that oral care prevention and treatment demands special attention from the health care institutions and authorities.