The utility of differentially expressed proteins discovered and identified in an earlier study (DeSouza, L et al. J. Proteome Res. 2005; 4: 377-386) to discriminate malignant and benign endometrial tissue samples has been verified in a 40-sample iTRAQ-labeling study involving normal proliferative and secretory samples, and Types I and II endometrial cancer samples. None of these proteins had the sensitivity and specificity to be used individually to discriminate between normal and cancer samples. However, a panel of pyruvate kinase, chaperonin 10, and a-1-antitrypsin, achieved the best results with a sensitivity, specificity, predictive value, and positive predictive value of 0.95 in a logistic regression analysis. In addition, three new potential markers were discovered, while two other proteins showed promising trends, but were not detected in sufficient numbers of samples to permit statistical validation. Differential expressions of some of these candidate biomarkers were independently verified using immunohistochemistry.