A writing instrument with an illuminated ink reservoir. The writing instrument includes a light source, a power supply, a power switch, and an ink reservoir defined by a portion of the instrument body that is generally capable of transmitting light. The ink reservoir contains ink, preferably flourescent marking ink that will glow brightly when illuminated by the light source. The writing instrument further comprises a light conducting member that guides the majority of light emitted from the light source into generally the center axis of the ink reservoir. The light conducting member helps to guide and focus the light into the ink within the reservoir. The light source may be an ultraviolet "black light", that causes the ink to glow brightly and produces a spellbinding visual effect. Advertising material may be imprinted on the instrument for advertising.