The technique of grazing incidence X-ray diffractometry (GIXRD) was used to study damaged layers in NaNd(WO4)2 and NaNd(MoO4)2 ceramics irradiated with high-energy ions. The possibilities and applicability limits of the technique for the analysis of such samples are shown. Estimates of the degree of amorphization in near-surface layers of ceramics are given depending on the irradiation dose. The higher resistance of NaNd(MoO4)2 ceramics to external radiation exposure as compared to NaNd(WO4)2 has been demonstrated.