Additionally, PSA/hK3, is the best tumour marker available in clinical medicine for diagnosing and managing prostate cancer (Diamandis, 1998; Barry, 2001), hK2 is useful for certain subgroups of prostate cancer patients (Magklara et al, 1999), hK6, 10 and 11, have recently emerged as potential serological epithelial ovarian cancer markers (Luo et al, 2001a; Diamandis et al, 2002), and several others possess clinical utility as prognostic/predictive markers (Diamandis and Yousef, 2001). This evidence concerns the gene KLK6 and prostate cancer.