Objective: To investigate the relationship between head impact characteristics and the levels of blood biomarkersassociated with brain injury, neurofilament light (NfL) and glial fibrillary acidic protein (GFAP).Methods: Four elite amateur Muay Thai athletes were equipped with impact monitoring mouthguards, collectinglinear and rotational acceleration data during a period of eight weeks. Capillary blood samples were collectedafter each period of sparring sessions to analyse the levels of NfL and GFAP.Results: On a group level, mean GFAP levels were negatively correlated to mean impacts per session (p < 0.05).Two athletes had significant correlations between head impact characteristics and the levels of NfL and/or GFAP.Conclusions: The results indicate that NfL and GFAP might responded differently to linear and rotational accelerationsand/or that the effect of different types of accelerations on brain tissue integrity is individual. Themethods used could be useful to monitor brain health in different impacts sports.