An OLED display is disclosed. In one aspect, the display includes a scan line transmitting a scan signal, a data line crossing the scan line and transmitting a data voltage, and a driving voltage line crossing the scan line and configured to transmit a driving voltage. The display also includes a switching transistor electrically connected to the scan line and the data line. The display further includes a driving transistor and a compensation transistor. A driving gate electrode and a driving drain electrode are respectively connected to a compensation source electrode and a compensation drain electrode. The display also includes a light blocking layer at least partially covering the compensation transistor and an OLED electrically connected to the driving transistor.