In this paper, we discuss logic circuit designs using the circuit model of three-state quantum dot gate field effect transistors (QDGFETs). QDGFETs produce one intermediate state between the two normal stable ON and OFF states due to a change in the threshold voltage over this range. We have developed a simplified circuit model that accounts for this intermediate state. Interesting logic can be implemented using QDGFETs. In this paper, we discuss the designs of various two-input three-state QDGFET gates, including NAND- and NOR-like operations and their application in different combinational circuits like decoder, multiplier, adder, and so on. Increased number of states in three-state QDGFETs will increase the number of bit-handling capability of this device and will help us to handle more number of bits at a time with less circuit elements.