Abnormal uterine bleeding (AUB) is one of the main clinical symptoms of the diseases of female internal reproductive organs. AUB cannot be considered as the specific symptom of a particular disease. To know the causes of AUB is necessary for rational treatment strategy. Aim. to study the peculiarities of endometrial state of the patients suffering from AUB and the combination of different forms of pathological endometrial (E) changes on the background of AUB. Material. the results of histological examination of endometrium (E) samples taken from 688 patients. Results. the structure of pathological changes of endometrium in case of AUB was identified. Conclusion. complex endometrial hyperplasia and atypical endometrial hyperplasia occur without any regularity on the background of various changes of E reflecting the state of both hypo- and hyper-estrogenia