In this work, we demonstrate all organic flexible polymeric optocouplers by utilizing a donor-acceptor bulk heterojunction polymer photodetector (PD) as the output unit and a polymer light-emitting diode (PLED) as the input unit. The input unit is a single-layer PLED on a glass or a plastic (PET) substrate utilizing a green emitting polyfluorene-benzothiadiazole copolymer in the active layer. The output unit is a single-layer PD on a glass substrate utilizing a P3HT:PCBM(1:1 by weight) blend, where P3HT is regioregular poly(3-hexylthiophene) and PCBM is (6,6)-phenyl-C61-butyric acid methyl ester. The electroluminescence spectrum of the PLED peaks at 530 nm and covers a spectral range that coincides quite well with the PD absorption spectrum (between 450 and 650 nm). The current density transfer ratio reaches 0.012% for an optocoupler that operates at 0 V and 15 V for the PD and PLED, respectively. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)