Introduccion y Objetivo: La caries dental y la fluorosis dental son problemas de Salud Publica que requieren sistemas de vigilancia y control en edades tempranas. El objetivo fue determinar la prevalencia de fluorosis dental en escolares de 12 anos, y la historia de caries en escolares de 5 y 12 anos en la Institucion Educativa Luis Eduardo Diaz del area urbana del Municipio de Yondo (Antioquia) durante el ano 2010. Materiales y Metodos: Estudio transversal en una poblacion de 62 escolares de 5 anos y 145 de 12 anos. Se realizo examen clinico y se establecio la experiencia de caries dental (indices ceo-d; 5 anos, COP-D; 12 anos) y la prevalencia de fluorosis dental (Indice de Dean). Se calcularon frecuencias, medianas y promedios por sexo en el caso de caries dental y prevalencia de fluorosis global y por grados de severidad. Calculo de razones de prevalencia de fluorosis por sexo con sus intervalos de confianza al 95% (RP, IC95%). Se analizaron las principales fuentes de agua del area de estudio. Resultados: El promedio ceo-d a los 5 anos fue de 2,37 ±3,39, con experiencia de caries del 61%. A los 12 anos se encontro un promedio COP-D de 0,73 ±1,28, y una experiencia de caries del 33,1%. No se encontraron diferencias estadisticamente significativas por sexo. La prevalencia global de fluorosis fue de 97,9%, con mayor prevalencia en hombres, aunque sin diferencias significativas (RP 1,05, IC95% 0,98- 1,12). El analisis fisicoquimico no mostro niveles altos de concentracion de fluor en agua. Conclusion: Se encontraron niveles altos de experiencia de caries dental a los 5 anos y alta prevalencia de Fluorosis a los 12 anos que exigen acciones de mejoramiento y estrategias en salud publica para esta poblacion. Abstract Introduction and Objetive: Dental caries and dental Fluorosis are public health problems, which require surveillance and control systems in primary ages. We aim to determine the prevalence of dental Fluorosis in school children age 12 and the caries experience of school children between 5 and 12 years old at the Institution “Luis Eduardo Diaz”, located in the urban area of the Municipality of Yondo (Antioquia, Colombia), during 2010. Materials and Methods: A cross-sectional study was conducted in 62 scholars of 5 years and 145 scholars of 12 years. Clinical examinations were carried out and the caries dental experience was established (DMFT and dmf indexes) and the prevalence of dental Fluorosis (Dean’s index). Prevalence, mean and median and for sex were estimated in case of dental caries and the global prevalence of Fluorosis and taking into account severity groups and sex. We calculate the prevalence ratio for sex and the 95% confidence intervals (PR, 95% CI). The main water sources of the study area were analyzed. Results: Mean dmf for 5 years was 2,37(±3,39) and the dental experience was 61%. At 12 years a DMTF mean was 0,73 (±1,28) and the dental experience was 33,1%. No statistical significance was found for sex. The global prevalence of Fluorosis was of 97,9%, the frequency was higher in males but the differences do not have statistical significance (RP 1z5, 95%CI 0,98- 1,12). The physicochemical analysis did not show high levels of fluoride concentrations in water. Conclusion: Higher levels of dental caries in case of scholars of 5 years dental Fluorosis for scholars of 12 years were found. Improvement actions and public health strategies are required for these populations.