Objective: According to the statistics, one in six men develops prostate cancer. There are several therapeutic options for prostate cancer. Anti-hormone therapy is one of treatment leading to an 80–90% remission. A significant percentage of men who received anti-hormonal treatment complain of decreased libido and erectile dysfunction. Similarly, these men may also suffer from hot flashes, weight gain, growth of [male] breast tissue (gynecomastia), lack of energy and initiative, depression and mental disorders. In this paper, I would like to present a therapeutic case of a man who received sexual counseling at the Israel Cancer Association, and who, upon receiving antihormonal treatment, changed his sexual orientation after having contracted prostate cancer. Design and Method: A series of meetings were conducted, encompassing an interview and sexual counseling. The Klein Sexual Orientation Grid (KSOG) was used in order to evaluate the patient’s sexual orientation. Results: According to the GRID several parameters such as sexual attraction and sexual behavior were significantly different in the comparison between the past and the present. Parameters such as social preference and hetero/gay style did not change. The remaining results will be presented. Conclusions: Following an analysis of this case, it may be concluded that a person’s sexual orientation can change during his lifetime. The hypothesis is that a life-changing event such as cancer, including all the side effects of difficult antihormonal treatments, has the potential to evoke a change in the person’s overall experience and in his sexual experience in particular.