[en] The method of non-destructive analysis for Al, Si and O in non-metallic inclusions isolated from steel is presented. The small powdered samples varying in mass from 2 mg to 40 mg were analysed, thus making the development of a proper technique of sample preparation necessary. The specific activition geometry and rotation of samples during irradiation were chosen to improve the accuracy and precision. Lower limits of determination for Al, Si, and O were 1.4 mg, 0.3 mg, and 0.8 mg, respectively. The presented work confirmed the possibility of applying neutron generator activation analysis to small samples with irregular shapes. For small samples (100 mg or less) when matrix effects are negligible, the determination limits are proportional to the disposed neutron flux density. The apparatus error of the Al and Si determinations was much greater than the value observed when analysing massive samples, which amounts to 3-6%. (T.G.)