The first LEDs based on oligothiophenes are reported. Polymer- based devices have the advantages that their physical properties can be tailored, they can be easily fabricated, and they can emit all colors, but they have poor stability, a high impurity level and low luminance. The systematic study of the electroluminescence properties of oligothiophenes described here is aimed to isolate the effects of various parameters, by controlling the structure of the used, and to extrapolate the results to polymers for use in LEDs.