We demonstrate ambipolar charge transport in organic field-effect transistors based on the solution processible methanofullerene [6,6]-phenyl-C71-butyric acid methyl ester (PCBM). The electron mobility measured in the linear and saturated regimes is approximately equal and of the order of 1×10-3 cm2/V¿s. In the linear regime, mobility is thermally activated with a strong gate bias dependence. The p-channel hole mobility is lower with a maximum value of 2×10-5 cm2/V¿s. The n- and p-channel operations are characterized by a low ( ~ |3| V) and a high ( ~ |50| V) switch-on voltage, respectively, with the on-off current ratio on the order of 104 for both channels. Although the present findings are qualitatively similar to those reported previously for C60-methanofullerene-based transistors, PCBM devices are more stable and easier to reproduce. By making use of this property we are able to demonstrate functional unipolar and complementarylike logic circuits with promising operating characteristics.