[en] The dosimetric films or tapes, for example standard sample of a dosimeter SO PD(F) 5/150 (Russia), are often used when dose fields are measured in a product irradiated by accelerator electron beams. The orientation of these films with respect to the beam direction may be fairly arbitrary. This is a source of a serious errors in the dose field measurement results, if that orientation is not taken into account. The error consists in an underestimate of the dose value up to 30-40%. The error is maximum for an unscattered beam (near the boundary of target) and for the angle between the film plane and the beam direction smaller than 20-30 deg. Besides that, a mean square-root error in these cases is about a factor of 1.5 larger. (author)