The prostate carcinoma (PCa) is the second most prevalent cancer and the fourth cause of death in Brazilian after 50 years old. It is an age related neoplasia, once the incidence increases gradually with time. The PCa has significant emotional importance rising conflicts related to male sexuality. In this study we evaluated the alterations in sexual behavior in men before and after the communication of the cancer diagnosis. Thirty patients were evaluated by clinical method using semi-directed interviews and questionnaire of quality of life. The data was submitted to analysis both quantitative descriptive and qualitative. Before the diagnosis 66.66% of patients informed active sexual life, 30% were inactive and 3.33% did not answered the questions. After knowing the diagnosis only 43.33% described active behavior and worse, decreased sexual satisfaction. In the group of patients without sexual activity there was an increase of the incidence from 30% to 53.3%. Often we observed depressive symptoms, anxiety, misunderstanding about the medical treatment and difficulties to maintain the everyday activities. We conclude that knowledge of PCa diagnosis alters significantly the psychological behavior where the sexuality is pointed out. For these reasons are needed interdisciplinary actions to patients with this tumor. The medical interviews should emphasize to the patients and relatives, information regarding the treatment, complications and their future perspectives.