Context:Abnormal uterine bleeding (AUB) is a common condition. A approach for establishing the cause using the FIGO PALM-COEIN classification system will help to make accurate diagnosis. Office hysteroscopy is leading method in diagnosis and treatment of AUB. Objective: To show that a new hysteroscopic method can be used in treatment of dysmenorrhea due to uterus bicornis unicollis with one rudimentary horn. Methods: To diagnose the patient we had performed 3D USG, CT and MRI. We confirmed duplication of the uterus most likely with two separate cervical channels and single vagina. The right cervical channel was extremely narrow and difficult to trace and fully evaluate even in the MRI. According to the ESHRE classification we established U4A- Robert’s uterus. Patients:18 year old patient with a 5 –year history of dysmenorrhea -severe pain worsening during menstruation. She had in 2012- appendectomy and in 2013 diagnostic laparotomy with releasing adhesions. She had no family history regarding gynecological pathology . Currently she was undergoing hormonal therapy with dienogest because of endometriosis suspicion. Intervention: There have been two treatment options: removal of the rudimentary horn in laparoscopy/ laparotomy. This method has been widely used, relatively safe but led to the fertility reducement-loosing one fallopian tube. Another new option has been preservation of the horn by hysteroscopic recommunication with the main cavity under supervision of simultaneous rectal ultrasound. This method has been individually adapted according to each patient case. We could have here the risk of perforation of the uterus but could preserve both fallopian tubes. After recanalization of the rudimentary horn we left folley catheter inside the new cavum for 72 hours. Result: The treatment has been successful- during over one year observation the patient has one cavum –created from unification of the two cavities , does not suffer from dysmenorrhea and is planning in the future pregnancy. Conclusion: A novel hysteroscopic treatment of uterine anomaly like Robert’s uterus seems a better and safe approach resulting in optimal long term outcome.