1. Various nonmetallic inclusions — oxides, brittle and plastic silicates, and globular bodies — may be encountered in high-speed steel. 2. High-speed steel is primarily contaminated by brittle inclusions the amount of which most frequently corresponds to numbers 3–5 of the TsNIIChM scale. Plastic and globular inclusions occurs comparatively rarely and in small quantities, corresponding to numbers 1–3. 3. High-speed steel contains mainly nonmetallic inclusions with a complex composition: complex silicates and silicate glasses with oxides, elongated in the direction of the metal fibers, or globular shaped. 4. For purposes of the best possible exposure of silicate glass inclusions with oxides extending in high-speed steel, the samples should be hardened from 1100–1200° prior to the preparation of the section of microexamination.