A trans-illumination device includes at least first and second sets of LEDs of two or more different colors arranged in a light head placed against a patients skin. The LEDs are mounted to a printed circuit board in the light head. An electronic control circuit is coupled to the light head by an electrical cable to selectively operate the LEDs in two or more user-selected modes, with the ability to adjust the relative intensities of the different colors to best suit the physiology of the patient. The light head may have a U-shape to surround an area of interest while providing ready access thereto. The light head may be used with a disposable, detachable cover having lenses for directing light from the LEDs into the patients tissues.