Introduction and Objective: Dental caries diagnosis during early childhood should be a priority in all health systems. The purpose of this study was to describe the initial dental caries situation in children with complete deciduous teeth, both genders, with lower and middle lower social-economic level from an urban area in Medellin. Materials and Methods: A randomly selected sample of 447 children between 2 and 4 years old was calculated; the sample was taken from the Susalud database, with 95% reliability, power of 80% and an error of 5%. A clinical test was performed by 3 calibrated examiners according to the International Dental Caries Detection and Assessment System (ICDAS) (Kappa 0.73 – 0.85). A WHO periodontal probe (11.5) was used for caries detection. Results: Treated and untreated dental caries prevalence of children was 74.7% with a specific mean of 9.7 ± 9.3 (SD), affected surfaces, prevalence of children having surfaces affected by non- treated dental decay was 74.9% while the dmf-s mean was 7.6 ± 7.7 (SD). 73.4% of children had at least one non-cavitated affected surface. Dental caries prevalence at “La Playa” Dental Clinic (70.2%) was higher than the “Itagui” Dental Clinic (62.8%) with a significant statistical difference (p value = 0.01 chi). The dmf-s mean according to Dental Clinic was 0.8 ± 2.7 (SD) in Itagui and 1.5 ± 3.9 at La Playa.Conclusions: The use of diagnostic systems that include non-cavited lesions is very important, the high percentage of decay at this age indicates the early presence of this illness, thus the importance of an early diagnosis and at the same time the implementation of specific treatment and prevention. Key words: Caries prevalence, Early childhood caries, Dental health.Rev.CES Odont.2009;22(2)27-34