We reported here the fabrication of an all-organic transistor built with metal-insulator-metal (MIM) junctions and its preliminary results. These planar samples consist basically of three interconnected tunnel junctions each one formed by an insulating film of poly(methyl methacrylate) (PMMA) sandwiched between two electrodes of polyethylene dioxythiophene/polystyrene sulfonate (PEDOT/PSS) assembled on a polyester flexible substrate. Electrical measurements were taken at room temperature, with a Keithley 2400 programmable semiconductor measuring system. The junctions presented individual capacitances of 1.40 pF. We observed an oscillatory variation of the drain current with the gate voltage. All associated capacitances were calculated for characterizing the transistor and the bottom electrode material.