Maintenance monotherapy with niraparib (Zejula; Tesaro), an inhibitor of poly(ADP-ribose) polymerase, improves progression-free survival in patients with relapsed high-grade serous epithelial ovarian cancers that are platinum sensitive, with or without germline mutations in BRCA1 and BRCA2.1–5 Clinical trials and the summary of product characteristics suggest that niraparib may not have adverse effects on the kidney.2,4,6,7 The purpose of this study is to describe kidney function parameters of patients followed up at our center for up to 12 months after initiation of niraparib therapy.