An organic light emitting diode (OLED) display is disclosed. In one aspect, the OLED display includes: i) gate wires positioned on a substrate in a first direction, ii) data wires positioned on the gate wires in a second direction crossing the first direction, iii) a pixel circuit including first thin film transistors respectively connected to the gate wires and the data wires and iii) an OLED connected to the pixel circuit. The first thin film transistor may also include a first active layer interconnecting the data wires and the OLED and including a channel region and source and drain regions doped with an impurity, and a first gate electrode positioned over the first active layer with first and second insulation layers sequentially interposed therebetween, wherein the second insulation layer is positioned on the channel region.