This paper provides an overview of the recent surgical intraoperative applications of indocyanine green (ICG) fluorescence imaging methods, along with the basics of the technology and instrumentation used. Over 200 papers describing this technique in clinical settings are reviewed, and other recent medical applications of ICG are briefly examined. The benefits of fluorescence imaging (FI) include high contrast and signal-to-noise ratio (SNR), making it a popular imaging mode in biomedical sciences. ICG has been used for decades in ophthalmology for retinal angiography, but its recent applications in various branches of surgical medicine are highlighted. The paper discusses the properties of ICG, such as its absorption maximum, confinement to the vascular compartment, low toxicity, and rapid excretion. It also reviews the instrumentation required for ICG imaging, including light sources, cameras, and filters. The surgical applications of ICG, particularly in neurosurgery and coronary surgery, are detailed, emphasizing the advantages of ICG in intraoperative monitoring of blood circulation. The paper concludes by discussing the potential for further technical developments in ICG imaging, such as rapid and reliable flow dynamics analyses and repeatable video playback loops.This paper provides an overview of the recent surgical intraoperative applications of indocyanine green (ICG) fluorescence imaging methods, along with the basics of the technology and instrumentation used. Over 200 papers describing this technique in clinical settings are reviewed, and other recent medical applications of ICG are briefly examined. The benefits of fluorescence imaging (FI) include high contrast and signal-to-noise ratio (SNR), making it a popular imaging mode in biomedical sciences. ICG has been used for decades in ophthalmology for retinal angiography, but its recent applications in various branches of surgical medicine are highlighted. The paper discusses the properties of ICG, such as its absorption maximum, confinement to the vascular compartment, low toxicity, and rapid excretion. It also reviews the instrumentation required for ICG imaging, including light sources, cameras, and filters. The surgical applications of ICG, particularly in neurosurgery and coronary surgery, are detailed, emphasizing the advantages of ICG in intraoperative monitoring of blood circulation. The paper concludes by discussing the potential for further technical developments in ICG imaging, such as rapid and reliable flow dynamics analyses and repeatable video playback loops.