Results of neutron diffraction measurements carried out for RAgSb 2 (R=Ce, Pr, Nd, Tb, Dy, Ho, Er, Tm) compounds are reported. All compounds crystallize in the tetragonal ZrCuSi 2 -type crystal structure and, except CeAgSb 2 , they are collinear antiferromagnets with the Neel temperatures between 11.1K for R=Tb and 2.0K for R=Tm. Below T c =9.5K CeAgSb 2 is a ferromagnet with the Ce magnetic moment equal to 0.33μ B and parallel to the c-axis. PrAgSb 2 has an antiferromagnetic structure of AF II type with the magnetic unit cell (a,a,2c). In the case of NdAgSb 2 a sine-wave-modulated magnetic ordering, described by the wave vector k=(0.5435,0,0), is observed. The compounds with R=Tb, Dy and Er order antiferromagnetically with the magnetic unit cell (2a,a,c). At T=1.4K the magnetic structure of HoAgSb 2 is similar to the one observed for TbAgSb 2 and DyAgSb 2 while at T=2.7K the peaks of magnetic origin correspond to a new incommensurate magnetic phase with the propagation vector k=(k x ,0,k z ). Up to the Neel temperature equal to 5.5K a commensurate antiferromagnetic structure and an incommensurate sine-wave-modulated one coexist. Two magnetic phases are also observed in TmAgSb 2 at T=1.4K. An increase in the temperature causes that the commensurate phase with the magnetic unit cell (2a,a,c) disappears. The magnetic moment is parallel to the b-axis in the case of R=Tb, to the [110] direction for R=Dy and parallel to the c-axis in the case of R=Er and Tm ones which correlates well with the respective signs of CEF B 0 2 -parameter. In HoAgSb 2 the magnetic moment lies in the b-c plane and forms the angle b =13.5 o with the b-axis at 1.4K. With increasing temperature the angle b increases up to 32 o about the Neel temperature. The obtained data are analysed in terms of the exchange interaction theory and crystal electric field.