A tissue illumination system and a method for harvesting a section of a blood vessel from a patient's body for further use. The tissue illumination system includes a light catheter inserted into a lumen of the blood vessel section to illuminate the vessel section and vessel side branches with an intensity which is visible to the physician from an exterior of the vessel section and also includes a viewing element insertable into the lumen and capable of viewing the illuminated vessel section. The tissue illumination system also includes at least one tool insertable into the lumen and used to harvest the vessel section.