Background: To present the safety profile of niraparib maintenance therapy in patients with platinum-sensitive recurrent ovarian cancer (PSROC) included in the NORA trial. Methods: The double-blind, randomized, placebo-controlled, multicenter, phase III NORA trial (NCT03705156) included adult (≥18 years) Chinese women with PSROC who received ≥2 prior lines of platinum-based chemotherapy. Post ≤8 weeks of the last chemotherapy, patients were randomized (2:1) to receive oral niraparib (300 mg/day or 200 mg/day for patients with bodyweight <77 kg or platelet count <150 × 10³/µL) or matched placebo. The primary endpoint was progression free survival, reported previously. Safety was assessed in terms of treatment emergent adverse events (TEAEs) related to hematologic toxicity (anemia/platelet count decreased and neutrophil count decreased) and non-hematologic toxicity (nausea/vomiting/constipation/insomnia/palpitations/hypertension). Adverse events (AEs) were graded using the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) v4.03. The data cutoff was February 1, 2020. Results: Of 265 patients included, the first 16 patients were given oral niraparib or matched placebo at a fixed starting dose of 300mg while 249 patients received individualized starting dose of niraparib (n = 166) or matched placebo (n = 83) based on baseline bodyweight and platelet count. The incidence of any TEAEs and grade ≥3 TEAEs was 100% and 50.8%, respectively in niraparib group, while 95.5% and 19.3%, respectively in placebo. Incidence of all grades of hematologic toxicity, gastrointestinal adverse events (nausea, constipation and vomiting), insomnia, palpitation and hypertension were highest in the first month after treatment with a gradual decrease in the further months. The median time to onset of grade ≥3 anemia, decreased neutrophil count and decreased platelet count were 87, 28, and 22 days, respectively, in the niraparib group. In niraparib group, any TEAEs that lead to dose reduction was observed in 59.9% of patients. Only 2 (1.1%) patients discontinued the treatment due to platelet count decreased and no patients discontinued niraparib treatment due to anemia or neutrophil count decreased. Overall, only 4% of patients in the niraparib group and 5.7% in the placebo group discontinued the treatment due to TEAEs. Conclusions: The lower incidence of TEAEs and the discontinuation rates indicate improved safety profile of niraparib with individualized starting dose in PSROC. Clinical trial information: NCT03705156