The application of Langmuir-Blodgett (LB) techniques to conjugated polymers offers a unique approach for constructing molecular devices. In this paper, we made thin film field-effect transistors (FET)-by LB techniques, based on regioregular poly(3-hexylthiophene) (RR-PHT). Langmuir films of RR-PHT were stable at the air-water interface and could be transferred onto hydrophobic substrates by horizontal deposition. The LB films prepared from three different methods were characterized by W-Vis absorption spectroscopy, polarized visible absorption, X-ray diffraction, reflective absorption IR spectroscopy, and field-effect mobility. The field-effect mobility of these FETs were among the highest of polymeric thin film LB FET devices.