Аннотация:AlB2-type ternary intermetallic compound Tb2Ni0.90Si2.94 (space group P6/mmm, hP3, No. 191) was reported to exhibit spin freezing behaviour of the ferromagnetic clusters present in the system below Tf = 9.9 K, along with the presence of spatially limited antiferromagnetic phase. In this work, on the basis of variable temperature zero-field neutron diffraction measurements, we have shown that the antiferromagnetic phase transition occurs for the compound below TN = 13 K. Neutron diffraction study indicates ab-plane non-collinear sine-modulated antiferromagnetic ordering of the system with wave vectors of k1 = [±1/6,±1/6, 0] and k2 = [±1/3,±1/3, 0] down to 1.7 K. The weak and diffuse nature of the magnetic Bragg peaks along with limited coherence length further confirm the short-range nature of the antiferromagnetic phase in this compound.