[en] Isostructural borides in Ln-Ni-B systems, where Ln-rare earth of yttrium subgroup are defined. It is noted that Ln₂Ni₁₀B₅ (Ln-Y, Gd, Tb, Dy, Er, Tm, Yb, Ln) borides have structure of Ho₂Ni₁₀B₅-type, sp.gr. Pbca, Z=8. Linear decrease in elementary cell parameters and volume indicate trivalent state of lanthanides in borides of the said composition