The technique to grow single-crystal polythiophene microwires by using self-assembly method was described. It is observed that the diffraction pattern does not change as the electron beam is moved along the microwire, indicating that the entire microwire is a single crystal. The growth of the architectures from solution is mainly governed by intermolecular interactions between the π-conjugated macromolecules. It is stated that the fabrication of 1D single-crystal polymer microwires represents a simple and potentially useful technique for organizing 1D microwires into highly integrated devices.