Hole transport in oriented films of poly (di-n-pentylsilane) has been studied in terms of the effect of the orientation and conformation of Si chain on the drift mobility and disorder of hopping sites. The results support the view that (1) the interchain overlap of wave functions for a 7/3 helix is higher than that for a transoid, (2) the hopping sites have higher diagonal and off-diagonal disorder in a 7/3 helix than in a transoid, and (3) the orientation of Si chains significantly enhances the interchain overlap of wave functions and reduces the diagonal (1/1.3) and off-diagonal disorder parameter (1/2.7) in a transoid but has no effect in the case of a 7/3 helix.