Fists, feet, knees, and elbows are muaythai weapons use during muaythai competitions. These may cause head and face injuries (HFI) and later diminish longevity of participants. Lack of precise methodological study in amateur muaythai restricted information to improve HFI prevention. The objectives of this study were, firstly, to analyze the causes of HFI in amateur muaythai boxers (AMB). Secondly, to determine relationship between external factors (not muaythai weapons) and HFI. Finally, to investigate the types and rates of HFI sustained in AMB. Video records and injury information from the amateur muaythai injury record form (AMIRF) of 341 AMB, obtained from three amateur muaythai competitions held in Thailand, were collected prospectively. Frame by frame technique was used to analyze cause, distribution, frequency, type, and rate of HFI resulting from muaythai weapons in conjunction with AMIRF. A total of 30 HFI occurred during 907 rounds (290 bouts) of Muaythai. The injury rate was 33.1 injuries per 1,000 rounds. The most common cause of HFI is a fist (18 injuries, 19.8 injuries per 1,000 rounds), followed by a foot (8 injuries, 8.8 injuries per 1,000 rounds); a knee (2 injuries, 2.2 injuries per 1,000 rounds); and an elbow (2 injury, 2.2 injuries per 1,000 rounds) respectively. A fist and a foot were most common in causing cerebral concussion (13 injuries, 14.3 injuries per 1,000 rounds and 7 injuries, 7.7 injuries per 1,000 rounds for a fist and a foot respectively). The differences in causes of types and sites of HFI were not statistical significant (chi-square = 20.580, p = .057 and chi-square = 12.246, p = .426). Grade 1 concussion occurred most frequently (10 injuries, 11.0 injuries per 1,000 rounds). Weight reduction was external factor may related to head and face injuries. In conclusion, punching and kicking were more dangerous than kneeing and elbowing, although all muaythai weapons can damage head and face.