Muaythai (Thai boxing, the national martial art of Thailand) has become increasingly popular worldwide. Many Thai children start training and being in boxing matches at very early ages; therefore they may be at risk for cognitive impairment, memory dysfunction, or brain disorders later in lives due to repeated brain injuries. To investigate for scientific evidences, neuropsychological tests, MRI, functional MRI (fMRI), and diffusion tensor imaging (DTI) were conducted on 108, 165, and 60 child boxers with 5 years of boxing experiences, respectively, as well as 200 age-matched normal controls (same socioeconomic status). Compared to the controls, over the increasing years of boxing experiences, decreased DTI FA (indicating white matter damage), increased DTI MD (representing loosening of the brain tissue) and increased MRI R2* (indicating accumulation of old blood product), decreased memory-task fMRI activations (suggesting brain injury along the limbic circuit), and decreased motor-task fMRI activations (reflecting better motor skill) were statistically significantly found in child boxers. However, increased fMRI activations were discovered at right motor cortex of the brain, perhaps, because the child boxers were able to better use left hands. The average IQ of the boxer was clearly decreased, and progressively decreased with longer years of boxing experiences. Should children be discouraged from Muaythai? Can we prevent them from the foreseeing brain damages while preserving the national-to-be-world heritage and improving child physical skills and health!