This indium-doped zinc oxide field effect transistor (IZO-FET) with a large ultraviolet (UV) detection sensitivity has been fabricated by inkjet printing technique. In darkness, the IZO-FETs exhibit a saturation current level of about 10 mA, an incremental mobility as high as 8 cm 2 V À1 s À1 , and a current on/off ratio of 10 4 –10 5 . When illuminated by 363 nm, 1.7 mW cm -2 UV light, the IZO-FET displays a photocurrent of 2 mA, and a darkness current of ~20 nA at an optimized gate voltage of -2 V. The device is effectively turned on in about 5 ms and off in 10 ms. These results suggest that the IZO-FET fabricated by inkjet printing could be a low cost highly sensitive UV photodetector.