The diagnosis of endometrial precancer (endometrioid intraepithelial neoplasia/EIN) remains a challenging area, with variable criteria and frequent disagreements even among expert gynecologic pathologists, potentially leading to under/overtreatment. In some studies, we systematically characterized potential biomarkers for EIN and identified novel potential biomarkers. In other research studies, we are using barcoded massively-parallel sequencing to identify mutations in biopsies and track their origin and allelic frequency progression. We are characterizing serial genomic alterations along the pre-EIN/EIN/cancer continuum in individual women. Preliminary findings indicate that genomic analysis of biopsies should be of diagnostic value, complementary to standard histopathological review of tissue sections.