Androgeno-deprivation is the treatment of reference for metastatic prostate cancer but it generates side effects which are too often ignored by physicians due to concentration on hopes of carcinologic benefit. Hot flashes, metabolic syndrome (body mass and lipid changes), decreased libido, erectile dysfunction, anemia, cognitive dysfunction, gynecomastia, decreased muscular mass and osteoporosis are the most frequent symptoms. They can and must be prevented by advice on physical activity and nutrition.