We present several fully printed organic complementary circuits using n- and p-type organic thin-film transistors. n-Type and p-type devices are developed on a flexible polyethylene-naphthalate substrate. All organic layers are deposited using a low-cost screen-printing technique. The inverters show a high gain and a switching point at exactly VDD/2. A seven-stage voltage-controlled oscillator (VCO) is designed with an organic output buffer, using the n- and p-type organic transistors. This VCO oscillates at a frequency of 186 Hz. Finally, two complementary differential amplifiers with high gain and large bandwidth are presented. The amplifiers only draw a 1-μA current from a 40-V power supply.