This is a multi-centre, phase II, open-label, two-stage design, single-arm study in patients with hormone-refractory prostate cancer (HRPC) with advanced (rising PSA) and/or metastatic disease and who have had prior anti-androgen therapy. The study will further explore the efficacy of E7389 by enrollment of patients into two strata: those who have had no prior systemic chemotherapy for their disease (except for mitoxantrone and estramustine), and those who failed no more than one previous chemotherapeutic regimen with tubulin-binding agents such as docetaxel.