This paper describes an experiment for assessing the discomfort glare caused by light emitting diodes (LEDs) having different colours. The results showed that coloured LEDs induce more discomfort glare than a white LED. On comparing different coloured LEDs, blue ones gave the highest glare perception, especially for those having shorter peak wavelengths. Different earlier proposed luminous efficiency functions for discomfort glare were applied to re-define luminance. This led to modified unified glare ratings, which achieved very accurate predictions of the visual results. A modified brightness based on a colour appearance model for unrelated lights was used to predict glare and also performed very well.