The new neutron diffraction data on magnetic structures of RT2X2 compounds, where R is a rare earth metal, T is a nd-electron transition metal and X is a p-electron metal are presented. For TbCo2Si2 and DYCo2Si2 compounds a transition from collinear antiferromagnetic AFI-type to the sine-wave modulated structure is observed near the Neel temperatures. The HoOs2Si2 shows an incommensurate magnetic order described by two wave vectors k(1)=(0.3,0,0) and k(2)=(0.22,0,0) in temperature range from 1.5 to 8.6 K - the transition temperature to a new also sine-wave modulated magnetic phase with the wave vector k=(0.3,0,0) stable up to the Neel point at 15.8 K. In TbOs2Si2, Tb magnetic moments form an incommensurate, sine-wave modulated structure with the wave vector k=(0.3185,0,0) and moments aligned along the tetragonal axis. At 1.5 K, the HoFe2Ge2 has a collinear antiferromagnetic structure described by the wave vector k=(0.5,0.5,0) with a small Ho magnetic moment equal to 4.5(1) mu (B) and a short-range magnetic order. The collinear magnetic structure disappears above 7 K, while the short-range contribution above 5 K.