This review article provides an overview of the recent surgical applications of indocyanine green (ICG) fluorescence imaging, the basic technology, and the instrumentation used. Over 200 clinical papers on ICG are reviewed, along with other recent medical applications. ICG is a near-infrared (NIR) fluorescent dye that has been used in clinical settings for over 50 years, particularly in retinal angiography. It is known for its high contrast, sensitivity, and ability to provide molecular information. ICG is also used in various surgical applications, including neurosurgery, cardiosurgery, and oncology, for intraoperative monitoring of blood circulation and vascular structures. ICG angiography (ICGA) is a technique that uses ICG to visualize blood vessels in the body. It works by illuminating the tissue with light at the excitation wavelength (around 750-800 nm) and capturing the emitted fluorescence at longer wavelengths (over 800 nm). This technique is simple and can be implemented with a few filters, a camera, and a light source. ICGA has been used in various surgical procedures, including neurosurgery, where it helps in identifying and differentiating blood vessels, and in oncology, where it is used for sentinel lymph node biopsy and cancer targeting. The properties of ICG include its high absorption maximum at 800 nm, its ability to bind to plasma proteins, and its low toxicity. ICG is also used in liver function assessment and in the evaluation of blood flow in the brain. However, there are challenges in its use, such as the need for specialized NIR imaging devices and the potential for phototoxicity. Recent developments in ICG include the use of ICG derivatives and other NIR contrast agents, as well as the development of new imaging techniques and devices. The instrumentation for ICG imaging includes cameras, light sources, and filters that are used to capture and process the fluorescence signals. The use of ICG in surgical applications has been shown to provide real-time information about blood flow and vascular structures, which is valuable for intraoperative decision-making. The review also discusses the potential for further developments in ICG imaging, including the use of advanced imaging techniques and the development of new contrast agents. Overall, ICG fluorescence imaging is a promising tool in surgical applications, offering a non-invasive and cost-effective method for visualizing blood vessels and assessing vascular health.This review article provides an overview of the recent surgical applications of indocyanine green (ICG) fluorescence imaging, the basic technology, and the instrumentation used. Over 200 clinical papers on ICG are reviewed, along with other recent medical applications. ICG is a near-infrared (NIR) fluorescent dye that has been used in clinical settings for over 50 years, particularly in retinal angiography. It is known for its high contrast, sensitivity, and ability to provide molecular information. ICG is also used in various surgical applications, including neurosurgery, cardiosurgery, and oncology, for intraoperative monitoring of blood circulation and vascular structures. ICG angiography (ICGA) is a technique that uses ICG to visualize blood vessels in the body. It works by illuminating the tissue with light at the excitation wavelength (around 750-800 nm) and capturing the emitted fluorescence at longer wavelengths (over 800 nm). This technique is simple and can be implemented with a few filters, a camera, and a light source. ICGA has been used in various surgical procedures, including neurosurgery, where it helps in identifying and differentiating blood vessels, and in oncology, where it is used for sentinel lymph node biopsy and cancer targeting. The properties of ICG include its high absorption maximum at 800 nm, its ability to bind to plasma proteins, and its low toxicity. ICG is also used in liver function assessment and in the evaluation of blood flow in the brain. However, there are challenges in its use, such as the need for specialized NIR imaging devices and the potential for phototoxicity. Recent developments in ICG include the use of ICG derivatives and other NIR contrast agents, as well as the development of new imaging techniques and devices. The instrumentation for ICG imaging includes cameras, light sources, and filters that are used to capture and process the fluorescence signals. The use of ICG in surgical applications has been shown to provide real-time information about blood flow and vascular structures, which is valuable for intraoperative decision-making. The review also discusses the potential for further developments in ICG imaging, including the use of advanced imaging techniques and the development of new contrast agents. Overall, ICG fluorescence imaging is a promising tool in surgical applications, offering a non-invasive and cost-effective method for visualizing blood vessels and assessing vascular health.