An organic electroluminescent display device employing a demultiplexer to reduce the number of output lines of a data driver. The display device uses the demultiplexer to store a data voltage in a data line, and supplies the stored data voltage to a pixel when a scan signal is applied, thereby displaying an image. Here, the data voltage supplied to the pixel is lowered because an electric charge is shared between a data line capacitor and a storage capacitor in the pixel. To compensate for the lowered data voltage, an auxiliary capacitor is provided for generating a compensation voltage. Here, the auxiliary capacitor increases the data voltage according to a level change of the scan signal. Therefore, a decrease in level of the voltage applied to the pixel is reduced or prevented so that DC/DC efficiency is enhanced without lowering a power supply voltage and a reference voltage.