The orientation and frequency-field dependencies of continuous wave electron paramagnetic resonance (EPR) spectra were measured for the first time for impurity Ho³⁺ ions in yttrium orthosilicate single crystal in the frequency range of 140 - 200GHz. The value of the zero field splitting of electron-nuclear levels and the magnetic characteristics of Ho³⁺ ions substituting yttrium in the Y2 crystallographic sites are determined.