An organic light emitting diode display includes a substrate, a scan line on the substrate to transfer a scan signal, a data line on the substrate to transfer a data signal, a switching transistor connected with the scan line and the data line, a driving transistor connected with the switching transistor, and an organic light emitting diode electrically connected to the driving transistor. The driving transistor may include a first semiconductor layer, the switching transistor may include a second semiconductor layer, and the first semiconductor layer may have a surface roughness that is greater than that of the second semiconductor layer.