We fabricated the flexible All-polymer field effect transistors (FETs) with optical transparency, whose all components were the organic polymeric materials. Active channel and all three electrodes were formed on a flexible polymer substrate using the simple photolithographic patterning technique of the electrically conducting poly(3,4-ethylenedioxythiophene) (PEDOT) or polypyrrole (PPy). Transparent photocrosslinkable polymers such as poly(vinyl cinnamate) or Epoxy/MAA polymer were used as the dielectric layer. We investigated the electrical characteristics of the FETs by measuring the source-drain current with sweeping the gate voltage. The source-drain current of the FETs decreased with increase of the positive gate voltage, implying the p-type FETs worked in the depletion mode. We believe the All-polymer FETs have significant advantages over other existing inorganic or organic FETs since the All-polymer FETs can be fabricated using the simple photolithographic process at room temperature and possess mechanical flexibility and optical transparency. (c) 2004 Elsevier B.V. All rights reserved.