The effects of testosterone on sexual appetite are obvious. Furthermore, treatment of hypogonadal men with testosterone leads almost always to unmistakable positive changes in mood, self-esteem and vitality. This testifies to the profound effects testosterone exerts on the brain and the mind. Conversely, hypogonadism and particularly the profound hypogonadism resulting from androgen deprivation treatment in men with prostate cancer, is associated with loss of vitality and mood disorders, if not depression. Several studies have found a role for testosterone on cognition (particularly visuo-spatial abilities), mood and depression, and low testosterone values may predict the development of Alzheimer's disease. Testosterone administration to hypogonadal men supports this notion. But not all studies have been able to confirm the association between testosterone and mental functions. These discrepancies might be explained by the large variations in design, inclusion criteria with regard to threshold values of testosterone, duration of study and psychometric instruments. It is likely that men with plasma testosterone values below the lower limit of normal will benefit (most). It is presently not justified to prescribe testosterone as a primary treatment for men with impaired cognitive functioning or mood disorders. These complaints are common in elderly men, and one of the diagnostic considerations might be testing for testosterone deficiency as an etiological factor, and if, upon laboratory measurement, testosterone levels are truly hypogonadal, testosterone treatment is warranted. This probably will not only benefit mental functioning but there will be somatic benefits as well as a result of normalization of testosterone levels. ß 2007 WPMH GmbH. Published by Elsevier Ireland Ltd.Mind-body interaction is evidently fundamental to human existence. But medicine has followed the Cartesian tradition of the split of the body and the mind. The body and the mind have subsequently become the domains of different scientific disciplines, each with different concepts and methodologies and it has been difficult to integrate their insights into one science. However, as a counter current, over the last 50 years psychosomatic medicine has promoted the scientific understanding of the interaction of body and mind, the interaction of brain and mind and the social context we live in. This has contributed to a better understanding of the pathogenesis, course and treatment of disease and has promoted health. This contribution will address the role of testosterone in the interaction of brain and mind, with a focus on the changes occurring in elderly men. The latter might be related to changes in androgen levels with aging. In an attempt to define the role of androgens in these processes, it is accepted that their effects relate to the complexity of the personality of the subjects living in their social context. Nevertheless, in spite of the fact that these processes are multifactorial it has been possible to define some elements that can be...