Background: Standard of care chemotherapy in patients (pts) with advanced ovarian cancer (AOC) is the combination of carboplatin and paclitaxel. Data from the PRIMA trial has shown a significant benefit in pts by the addition of a maintenance treatment (MT) with niraparib irrespective of BRCA or HRD-status in high-grade ovarian cancers (OC). The PAOLA-1 trial evaluated MT in pts with AOC with the combination of olaparib and bevacizumab and has also shown a significant benefit compared to bevacizumab monotherapy. However, it is unclear if a PARP-inhibitor (PARPi) MT monotherapy is sufficient or if the addition of bevacizumab is needed. Therefore, we investigate, if the treatment strategy of carboplatin / paclitaxel / bevacizumab / PARPi is superior to the treatment of carboplatin / paclitaxel / PARPi in an all-comer population. Methods: AGO-OVAR 28/ ENGOT-ov57 (NCT05009082; EudraCT Number: 2021-001271-16) is an Arbeitsgemeinschaft Gynäkologische Onkologie (AGO) Study Group led, international, multicenter, randomized, prospective phase III trial within the ENGOT trial network. The trial population is composed of adult pts with newly diagnosed, advanced high-grade epithelial OC, primary peritoneal cancer or fallopian tube cancer FIGO III/IV (except FIGO IIIA2 without nodal involvement). All pts should have completed the first cycle of chemotherapy (carboplatin and paclitaxel) as part of Study Run-In-Period. Prior to day1 of cycle2, pts with a valid central tumor BRCA (tBRCA) test result will be randomized 1:1 into either Arm1 and will receive 5 additional cycles of carboplatin and paclitaxel, q21d followed by niraparib for up to 3 years; or into Arm2 where pts will receive 5 additional cycles of carboplatin and paclitaxel plus bevacizumab, q21d followed by bevacizumab, q21d (for up to 1 year) and niraparib for up to 3 years. Patients who are scheduled for neoadjuvant chemotherapy and interval debulking surgery are also allowed to be included in the trial. The primary objective is progression free survival (PFS). Secondary objectives include but are not limited to: PFS according to tBRCA-status, overall survival, PFS2, safety and tolerability, and quality of life. The trial will start in Q1/2022 with First Patient First Visit expected in Q2/2022. It is planned to recruit 970 patients. Clinical trial information: NCT05009082.