Color vision is the ability to make discriminations based on the wavelength composition of light. Intact color vision is mandatory for selection of posts related to driving, traffic services, railways and armed forces. Color perception may be influenced by a variety of factors of which intensity of ambient light is the most important. The optimum intensity of light for testing the color vision is not clearly defined. So there is a need to evaluate that optimum intensity of light to be used for carrying out color vision testing. OBJECTIVE: To evaluate the optimum intensity of light for testing color vision. METHODOLOGY: 90 subjects in the age group between 15-25 years are subjected to color vision testing using Ishihara's chart in different intensities of light in a dark room. The subjects are instructed to read the numbers or trace the lines in each plate of the book at different intensities of ambient light. The intensity at which the subject is able to perform best is noted and the data is statistically analyzed. RESULTS: The number of choices read incorrectly was more with illumination less than 60W and was statistically significant (P <0.05). Color perception was found to be better at higher intensities of light-60W, 100W, 200W and in natural daylight and showed no significant difference. There were no statistically significant differences between males and females in color perception in different intensities of light. CONCLUSION: The intensity of light of carrying out color vision testing should not be less than 60W and natural day light is found to be ideal