BACKGROUND Despite the need for oral health morbidity surveys to aid in reviewing of the oral health services, dental data of Ugandan children is scanty. OBJECTIVE To describe the magnitude and distribution of selected oral health conditions among primary school children in Mbarara, Uganda. METHODS A stratified two-stage cluster sample of 437 children aged 5-6, 8-9 and 11-12 was enrolled. The selected conditions included: dental caries, plaque, calculus, gingivitis, fluorosis and malocclusion (maxillary overjet). These conditions were diagnosed and scored in accordance with World Health Organisation (WHO) criteria. RESULTS The mean decayed, missing, filled permanent teeth (DMFT) was 1.5(±0.8 SD). Females had higher DMFT (1.6±0.8SD) than males (1.3±0.8SD). Decayed, filled milk teeth (dt) was 2.7(±1.8SD) but more in males 3.1(±2.1SD) than in females 2.4(±1.6SD). Children in private schools were likely to have more caries in both permanent teeth (DMFT: 1.6±0.9SD) and milk teeth (dt: 3.0±1.9SD). Day-scholars were likely to have more caries in permanent teeth (DFMT: 1.50.8SD). Those in boarding were likely to have more caries in milk teeth (dt: 3±2.2SD). Milk teeth caries decreased with age (p<0.0001). Eight (1.8%) had very mild to moderate fluorosis. Nine (2%) lost permanent canines due to practice of "nylon teeth mutilation." Majority 325(75%) had dental plaque, which increased with age (p<0.0001). Males significantly had plaque. Children in private schools were associated with less plaque (OR: 0.6, 95%CI: 0.4-0.9), as were those in boarding schools. Some 113(25.9%) had calculus that increased with age (p<0.0001). Calculus was more prevalent in males, government schools, and among day-scholars. Females were less likely to have maxillary overjet (OR: 0.5, 95% CI: 0.3-0.8). Day-scholars were 2 times more likely to have maxillary overjet (OR: 1.9, 95%CI: 1.1-3.5). None had severe gingivitis. CONCLUSIONS The oral hygiene of school children was poor with high plaque prevalence demonstrating a lack of established oral hygiene practices. A comprehensive community-focused oral health care intervention that includes oral health education in homes and the strengthening of school health programme is needed to improve the oral health status of children in Mbarara.