Objectives: In the phase III SOLO1 trial (NCT01844986), maintenance olaparib provided a substantial progression-free survival benefit in patients with newly diagnosed, advanced ovarian cancer and a BRCA mutation who were in response after platinum-based chemotherapy. We analyzed the timing, duration and grade of the most common hematologic and non-hematologic adverse events in SOLO1. Methods: Eligible patients were randomized to olaparib tablets 300 mg twice daily (N = 260) or placebo (N = 131), with a 2-year treatment cap in most patients. Safety outcomes were analyzed in detail in randomized patients who received at least one dose of study drug (olaparib, n = 260; placebo, n = 130). Results: Median time to first onset of the most common hematologic (anemia, neutropenia, thrombocytopenia) and non-hematologic (nausea, fatigue/asthenia, vomiting) adverse events was <3 months in olaparib-treated patients. The first event of anemia, neutropenia, thrombocytopenia, nausea and vomiting lasted a median of <2 months and the first event of fatigue/asthenia lasted a median of 3.48 months in the olaparib group. These adverse events were manageable with supportive treatment and/or olaparib dose modification in most patients, with few patients requiring discontinuation of olaparib. Of 162 patients still receiving olaparib at month 24, 64.2% were receiving the recommended starting dose of olaparib 300 mg twice daily. Conclusions: Maintenance olaparib had a predictable and manageable adverse event profile in the newly diagnosed setting with no new safety signals identified. Adverse events usually occurred early, were largely manageable and led to discontinuation in a minority of patients.