The aim of the study was to present a new EIN classification of premalignant endometrial lesions. The diagnosis of precancerous disease of the endometrium remains non-standardized because the most widely used World Health Organisation classification is a poorly reproducible system, which does not specify objective architectural criteria for each category of hyperplasia and does not correspond to appropriate clinical management (undertreatment, overtreatment of the lesions). The new proposed EIN diagnostic schema, based on integrated morphological, genetic molecular, objective histomorphometric (D-score) and clinical outcome studies, divides endometrial lesions into three categories: benign hyperplasia, endometrial intraepithelial neoplasia, and cancer.