Objective: To determine the prevalence of oral diseases in children 6, 12 and 15 years old in Islay, Arequipa. Materials and methods: Observational, descriptive and cross-sectional study. The sample consisted of 360 students of 6, 12 and 15 years of age of both sexes who met the inclusion criteria. The level of confidence was determined at 95% and the margin of error at 5%. To evaluate oral pathologies, the OHI-S, OHI-M, mPI/PI, DMFT, DMFS, the WHO and the Dean index were used. The students were examined visually and clinically. Results: Regarding IHO-S: good hygiene was observed in 72.5% in deciduous and 63.3% in permanent teeth; regular hygiene was found in 27.5% in deciduous and 35.0% in permanent teeth with poor hygiene in 1.7% in permanent teeth and significant differences in age. The CPOD showed 6.71 carious, 0.14 lost, 1.44 blocked and an average of 8.29 with significant differenc...