We asked in this study if the quantitative sonographic analysis could diagnose effectively the benign and malignant tumors of the parotid gland. Sonographic analyses using mean grey values and SDs of echo levels were performed on the 21 benign tumors and 22 malignant tumors of the parotid glands. Both the mean grey level and the SD of the echo levels were significantly and characteristically different among the different parotid tumor groups. Discrimination analysis showed that, compared with single uses, a combined use of these two criteria improved diagnostic accuracy to 81% (carcinoma vs. pleomorphic adenomas), 93% (malignant lymphomas vs. pleomorphic adenomas), 91% (carcinomas vs. malignant lymphomas), 100% (pleomorphic adenomas vs. Warthin's tumors), 100% (carcinomas vs. Warthin's tumors) and 100% (malignant lymphomas vs. Warthin's tumors). These findings suggest that quantitative sonographic analysis is effective in differentiating benign and malignant tumors of the parotid gland.