Summary. -Rotavirus is the most common cause of gastroenteritis in children up to fi ve years of age worldwide. Th e aim of the present study was to analyze the genotypes of rotavirus strains isolated from children with gastroenteritis, aft er the introduction of the rotavirus vaccine in México. Rotavirus was detected in 14/100 (14%) fecal samples from children with gastroenteritis, using a commercial test kit. Th e viral genome was purifi ed from these samples and used as a template in RT-PCR amplifi cation of the VP4 and VP7 genes, followed by gene cloning and sequencing. Among the rotavirus strains, 4/14 (28.5%) were characterized as G12P [8], 2/14 (14.3%), as G12P (not typed), and 3/14 (21.42%) as G (not typed) P [8]. Phylogenetic analysis of the VP7 gene showed that G12 genotypes clustered in lineage III. Phylogenetic analysis revealed that VP4 genotype P[8] sequences clustered in lineage V, whereas other P[8] sequences previously reported in Mexico (2005Mexico ( -2008 clustered in diff erent lineages. Rotavirus genotype G12 is currently recognized as a globally emerging rotavirus. To our knowledge, this is the fi rst report of this emerging rotavirus strain G12P [8] in México. Ongoing surveillance is recommended to monitor the distribution of rotavirus genotypes and to continually reassess the suitability of currently available rotavirus vaccines.