AbstractInvestigated is the beamshift which a polarized electromagnetic wave undergoes while being reflected at the boundary of a trigonal medium. It is shown that beamshift tends growing toward large values within two small ranges in the nearest vicinity of both of the limiting angles of total reflection. The two maximum values of shift depend on the angle ϵ between the optical axis and the normal of the separation plane as well as of the azimuth ζ of the plane of incidence inspite the main section of the separation plane. The effect of beamshifting has been found to be the more evident, the less the absorptive powers in the two mediae do diffe