ABSTRACTFully flexible and transparent all organic field effect transistors were fabricated by means of an innovative and inexpensive technique. A 1.8μm thick polyethylenetetherephtalate sheet, Mylar® (Du Pont), was used as gate dielectric and at the same time as mechanical support for the whole structure. We used pentacene, deposited by thermal sublimation, as semiconducting layer, whereas poly(ethylene-dioxythiophene)/polystyrene sulfonate (PEDOT/PSS) was used for the realization of the electrodes. Gate electrodes were realized by spin coating, while source and drain electrodes were patterned by micro-contact printing. We fabricated typical p-type field effect transistors, with mobilities up to 2 × 10−1cm2/Vs and Ion/Ioff up to 105, in a very simple and inexpensive way. It is worth to note that this technique allows the realization of bottom contact and top contact transistors. We realized both bottom contact and top contact devices on the same substrate and with the same active layer and we investigated how the structure itself and the active layer morphology influence the electrical properties in terms of hole mobility, Series Contact Resistance and parasitic capacitance effects. The comparison between top-contact and bottom-contact devices shows interesting marked differences that can be mainly attributed to a different PEDOT:PSS/semiconductor interface quality, influencing the most meaningful parameters. The flexibility of the obtained structure and the easy scalability of the technological process, suitable for roll to roll mass production processes, open the way for economic production of high-resolution organic devices