Non-dispersive transient currents in non-homogeneous films with a single discrete trap level have been calculated, the non-homogeneity consisting in spatial variations of trap depths or the presence of constant built-in electric fields in the limit cases of shallow and deep traps. Both kinds of spatial non-homogeneity may result in identical shapes of transients. Methods for determination of the spatial variations of trap depth and internal built-in electric field on the basis of experimental data are discussed.