[en] The experimental results on heating of a dense plasma by electron beam (1 MeV, 40 kA, 4μs) on the GOL-3 device are presented. The relativistic electron beam is injected into a 7-meter long plasma column of a mirror machine). The beam deposits about 20-30% of its energy into 'hot' (1-10 keV) plasma electrons in the homogeneous part of plasma (n - 10¹⁵ cm^-3, T∼ 1 keV). These electrons are slowed down in a 0.5-3 meter long gas cloud of a density of 10¹⁶-10¹⁷ cm^-3 (so-called two-stage heating scheme). The 'hot' electrons ionize the cloud, create a plasma which is heated due to binary collisions. The resulting total energy of the cloud is 2-4 times greater than the instantaneous energy content of the lower density homogeneous plasma. The shock waves were observed in the plasma. Temperature distribution along the plasma cloud was measured and was used to estimate the average energy of 'hot' electrons. The experiment demonstrates a high efficiency of the two-stage scheme of a dense plasma heating. 38 refs.; 28 figs