The effect of ion irradiation on the strength characteristics of magnesium oxide and ceramics based on zirconia is studied. The MgO samples were a single crystal grown in an artificial manner. Samples of zirconium ceramics were prepared by ceramic technology. Irradiation of MgO crystals was carried out by Si+ ions (E = 150 keV), Fe+ (E = 70 keV), C+ (E = 50 keV) at room temperature. The fluence varied within the range (1016-1017) сm-2. The modification of the investigated types of ceramics was carried out by ions Al+ (Е = 60 keV), Ar+ (Е= 60 keV), N+ (E = 50 keV). We used ion beams of microsecond duration and moderate power (the current density in the pulse was 3 10-3 A/cm2). Fluence was 1017 cm-2. The irradiation of the ceramics with an ion beam C+ (E = 50 keV) was also performed with nanosecond duration (τ = 50 ns). It is established that ionic irradiation of magnesium oxide leads to an increase in crack resistance and a critical stress intensity factor. Irradiation of ceramics leads to hardening of its near-surface layers.