Purpose and Specific Aims The primary purpose of this pilot study is to explore the relationship between mitochondria and fatigue in men diagnosed prostate cancer. The specific aims are to: (a) describe levels of mitochondrial enzymes, (b) examine relationships between levels of mitochondrial enzymes, fatigue, and health-related quality of life (HRQOL); and (c) compare levels of mitochondrial enzymes in men with and without fatigue.