Urinary gonadotropin peptide (UGP) was measured in 866 urines from normal women and women with benign and malignant gynecologic disease using the Triton UGP enzyme immunoassay. The greatest level of overexpression of the marker was observed in patients with ovarian cancer. Using a cutoff of 4 fmol/mg creatinine, UGP was overexpressed in samples from 2% of normal premenopausal women, 15% of normal postmenopausal women, 5% of women with benign gynecologic disease, and 59% of women with ovarian cancer. UGP expression was independent of the histologic type of ovarian cancer. The expression of UGP and CA 125 were not correlated and use of the two markers in tandem increased the sensitivity of detection of disease by greater than 20% over that which was observed using each marker individually. UGP levels were correlated with clinical status, and doubled in value in 67% of patients with progressive disease, and were halved in 93% of patients who were in remission at the time of the study.