Electron and hole drift mobilities were measured by the time-of-flight technique in films of aromatic polyimides based on 9,10-bis(p-aminophenyl)anthracene or 9,10-bis(phenylthio)anthracene and a series of diimide fragments. The electric field and temperature dependences of the mobilities were detected. In amorphous films of the soluble polyimide, the drift mobility was found to reach the value of 10(-4) cm(2)V(-1)s(-1) at 5.5x10(5) Vcm(-1). In the insoluble polyimides films, the mobility was lower by one or two orders of magnitude. This is attributed to the presence of cavities in the films of the insoluble polyimides.