A general method for the rating of nonmetallic inclusions in steel by use of a quantitative television microscope (QTM) has been developed. The discussion of the method includes a special automatic specimen preparation procedure and a simplified statistical test to indicate the reliability and precision of the data. Information obtained with the QTM consists of area fraction of inclusions, number of inclusions, and distribution of inclusion lengths. These QTM parameters, or the values derived therefrom, have been used to express the overall inclusion rating for steel products and for comparison with standard rating methods. Steels have been ranked according to cleanliness by values derived from the QTM method similar to the ranking by values derived from inclusion rating methods described in ASTM Designation E 45. The QTM method has been shown to be versatile and to improve reproducibility by eliminating most of the variation due to human judgment.