Infrared thermography is used for measuring and analyzing physiological functions and pathology related to the body’s thermal homeostasis and temperature. This review provides an overview of the technological advantages of infrared imaging, with the focus on new advances in and opportunities for infrared imaging, as a reliable medical diagnostic tool. The review has four main parts. Firstly, a short history of thermography development in medicine is given. Secondly, an overview on the clinical and biomedical research results and methodological improvements in established applications of infrared thermography is provided. Thirdly, the details of published research and development results and activities of the last 3 years for time and frequency domain analysis of infrared video thermography recordings to study some vital functions of human physiology are discussed. Analysis of infrared video thermography streams resulted in important information on microvascular (arteriolar) function of the skin and of vital organs when exposed during an operation. This new set of parameters of microvascular function enhances the assessment of the cardiovascular system in chronic diseases e.g. in hypertension and diabetes. Infrared thermography provides valuable information when an organ’s suitability for transplantation must be assessed based on quantifiable parameters of organ function and viability. Fourthly, a brief overview on a separate, exciting area of infrared imaging is provided as well: the development of a touchless polygraph system. It enables the study of the psychophysiological parameters of stress, by the assessment of breathing and pulse wave patterns by noncontact methodology, for lie detection purposes. In conclusion, infrared imaging is a non-invasive, non-radiative, low cost detection tool, and its application area is constantly growing, along with technical improvements and advances.