['The purpose of this study was to determine the independency of a nadir CA-125 level as a prognostic factor in patients with advanced epithelial ovarian cancer (EOC).', 'Among the 153 women with advanced EOC who had surgery in our hospital between January 2001 and June 2007, 121 women underwent retrospective chart review.', 'Sixty-six patients (57.9%) had nadir CA-125 values < or =10 U/ml. The CA-125 levels at the time of diagnosis was associated with the nadir CA-125 (P = 0.018). The median progression-free survival (PFS) in patients with nadir CA-125 levels < or =10 and 10-35 U/ml was 32.4 and 16.8 months, respectively (P = 0.0001). A multivariate Cox hazard model revealed that the nadir CA-125 value and the residual tumor size > or =0.5 cm were independently associated with the PFS (P = 0.001 and 0.014). Within the subgroup who underwent primary debulking surgery, the significant association between the PFS and the nadir CA-125 value was preserved (P = 0.001).'] Is nadir CA-125 level an independent prognostic factor in advanced epithelial ovarian cancer?