We have easily fabricated channel patterns of organic field-effect transistors (OFET), in which channel lengths were ca. 5 gm, by using wet-spun poly (3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS) microfibers with diameters of ca. 5 mu m. Pentacene-based OFETs with a bottom-contacted configuration, fabricated on the channel patterns, showed a hole mobility of 10(-3) cm(2) V-1 S-1 simply reflecting FET characteristics of the pentacene, and showed large current of 8 mu A (V-DS = -50 V; VG = -50 V) reflecting shorter channel length of the devices.