Backround LLANTO scale has not been validated in colombian population until now. It is intended to validate the pain scale LLANTO in neonates and children under 5 years treated at two institutions. Methodology: We included children with any kind of acute pain, classifying them in two groups: neonates and infants between 1 month and 5 years attended at Foundation Cardioinfantil and Major University Hospital. The scales were applied by two pediatric residents and a nurse. A pilot test was performed and the difficulties were corrected. The LLANTO scale was applied and compared with the PIPP and FLACC scales, depending on the age group. Statistical analysis of correlation between the applied scales were made by ANOVA test and the correlation test between the three evaluators using the CCI. For its interpretation the results of greater than 0.80 were considered as excellent. Results: 44 patients were included in each group. In neonates the CCI during the initial evaluation showed a very good result (ICC 0.86) and an excellent result (ICC 0.92) one hour later in the control. In the group of children under the 5 years-old the ICC showed a good result in the initial assessment (0.63) and a very good result (ICC 0.89) one hour later during the control. ANOVA 0.01. Discussion: Statistically significant results between LLANTO scale and FLACC and PIPP and scales were found, proving the validity of the LLANTO scale as measured tool for evaluating the pain in neonates and children under 5 years in our Colombian population
