We report on ac conductivity measurements carried out onpoly(o-methoxyaniline)films, of high molecular weight, at different doping levels. The results are typical of a disordered medium showing a constant conductivity at low frequencies and rising for higher values. In order to interpret the results, we use a model which takes into account that the sample is composed of an insulating disordered matrix sprinkled with conductive islands generated by doping, as indicated by energy dispersive x-ray microanalysis. It comes out of the fitting that the doping induces an increase in the carrier mobility, instead of increasing the density of carriers. ©1997 American Institute of Physics.