This study is being done to evaluate the safety and efficacy of atrasentan in men with metastatic hormone-refractory prostate cancer.

Inclusion Criteria:

• Diagnosis of prostate cancer.
• Rising PSA while on hormonal therapy or following surgical castration.
• Documented evidence of metastatic disease.

Exclusion Criteria:

• Have received cytotoxic chemotherapy.
• Have received opioid or narcotic medications (such as codeine or morphine) or radiation for pain caused by your prostate cancer in the last 6 months.