D.O. Ott was born in 1855 in the family of the vice-governor of the Novgorod province O.F. Ott. In 1874 he graduated from the Novgorod gymnasium and entered the St. Petersburg Medical-Surgical Academy, which he graduated in 1879. In 1881, D.O. Ott passed the exam for a doctor of medicine. In 1884 he defended his doctoral thesis. Having received the title of private assistant professor at the Medical-Surgical Academy, in 1885 Ott began teaching at the Imperial Clinical Institute of the Grand Duchess Elena Pavlovna. At the same time, he supervised the Alexander Nevsky maternity hospital. In the rank of Professor D.O. Ott was approved in 1889. From 1893 he was appointed director of the Imperial Clinical Midwife Institute. In 1899–1906 - Director of the St. Petersburg Women's Medical Institute. In 1895, D.O. Ott became the life obstetrician of the Imperial Court. In 1899, D.O. Ott introduced the method of ventroscopy into clinical practice, and on April 19, 1901, for the first time, he reported it at a meeting of the Petersburg Obstetric-Gynecological Society. For its implementation of the D.O. Ott developed special tools, used the air for pneumoperitoneum, the high position of Trendelenburg, equipped the operating table with special devices for supporting the patient's legs and shoulders. April 26, 1906 through colpotomic access after removal of the uterus with appendages D.O. Ott performed the world's first transvaginal appendectomy. He also performed ovariotomy, dissection of intra-abdominal adhesions, becoming the first surgeon in the world to perform endoscopic interventions on the abdominal organs, i.e. He was the ancestor of the world endoscopic surgery. D.O. Ott was one of the founders and chairman of the Petersburg Obstetrician-gynecological Society (1912), founder and editor-in-chief of the Journal of Obstetrics and Women's Diseases. They published more than 145 scientific papers, including 5 monographs devoted mainly to issues of operative gynecology. BEFORE. Ott was an honorary member of Russian and foreign (Berlin, Italian, Egyptian and other) scientific medical societies. In 1924, a bronze monument to the professor was installed on the main staircase of the institute, and in 1989 the Research Institute of Obstetrics and Gynecology of the Russian Academy of Medical Sciences was named after him. Dmitry Oskarovich Ott died at the 74th year of his life in 1929 in Leningrad and was buried at the Novodevichy cemetery.