The goal of the current study was to examine variants in seven key circadian rhythm genes (BMAL1, CRY2, CSNK1E, NPAS2, PER3, REV1, TIMELESS) and two transcription factors (KLF10 and SENP3) activated by circadian rhythm gene expression as risk factors for epithelial ovarian cancer, histopathologic subtype, and invasiveness. The gene discussed is PER3; the disease is ovarian carcinoma.