INTRODUCTION: The last two decades have seen an exponential growth in the distribution and availability of child pornographic material on the Internet and social networks. The medical community is involved in assisting the investigating authorities in relation to estimating the age and sexual maturity of the alleged victims. OBJECTIVE: To determine the efficacy of using Tanner stages as a method for esti mating chronological age in alleged child pornography cases based on published evidence. MATERIAL AND METHOD: Systematic review study in PubMed and Scopus databases following PRISMA guideli nes. Articles describing the outcome of using Tanner stages to estimate chronological age in alleged child pornography cases were identified. For screening, those written in English or Spanish published from January 1, 2000, to April 30, 2020, were considered. The following data were extracted from the articles included: type of study; material and methods used; Tanner items examined; evaluators' characteristics; results; estimated chronological age versus real age; observer-dependent variations (bias); and conclusions. RESULTS: Seven studies were included. Three were literature reviews and four were case studies with expert testimony and observer bias. This method is ineffective when the alleged victim, in both sexes, shows sexual maturation in Tanner stages 3-5. In stages 1-2, it may be useful to state that the victim is under 18 years old, but not to determine their chronological age. CONCLUSION: Scientific evidence discourages the use of Tanner stages to estimate the chronological age of the vic tim from images in alleged child pornography cases. Pediatricians, and other medical professionals, should avoid making a testimony that is not scientifically based.