Purpose: The purpose of this systematic review was to evaluate the evidence regarding injury and poisoning associated with the clinical mercury thermometer. Methods: Electronic literature searches were conducted for identification of relevant studies and case reports of injury and poisoning associated with the clinical mercury thermometer. The search outcomes were limited to literature with English and Korean languages published from 1966. Studies related to occupational mercury exposure, or mercury exposure from sphygmomanometer, barometer, and fluorescent light were excluded. Results: A total of 60 reports, including 59 case reports, were finally included. Of those, nine cases pertained to an intact thermometer as a foreign body, 25 injuries were related to a thermometer, and 26 cases involved exposures to mercury from a broken thermometer. Case reports were classified according to severity into 16 mild, 41 moderate, and two severe cases. Two cases of mortality were reported, one was deliberate intravenous injection of mercury and the other was acute vapor inhalation of mercury from broken thermometers. Conclusion: Findings of this systematic review suggested that the mercury thermometer could cause various forms of poisoning and injury. In particular, inhalation of mercury vapor from a broken thermometer can lead to systemic toxicity requiring chelating therapy.