Abstract: System and method for enhancing visualization of veins, arteries or other subcutaneous natural or foreign structures of the body and for facilitating intravenous insertion or extraction of fluids, medication or the like in the administration of medical treatment to human or animal subjects are described which comprise a light source (11) for illuminating or transilluminating the corresponding portion of the body with light of selected wavelengths and a low-level light detector (12) such as an image intensifier tube (including night vision goggles), a photomultiplier tube, photodiode or charge coupled device, for generating an image of the illuminated body portion, and optical filter(s) (17) of selected spectral transmittance which can be located at the light source(s) (11), detector (12), or both.