of testosterone in spermatogenesis is now better de­ fined. We have a more complete understanding of the psychotro­ pic effects of testosterone and know so much about the different target organs and functions that individual chapters deal with testosterone and the prostate, lipids and the cardiovascular sys­ tem, hair, bones and muscles. The general chapter on pharmacol­ ogy and clinical uses of testosterone, in particular in male hypo­ gonadism, is extended by pharmacokinetic studies on testoster­ one preparations and individual substitution modalities using testosterone esters as well as implants and advanced trans dermal applications. The physiologic basis and possible clinical applica­ tions of testosterone in non-gonadal diseases, in male senes­ cence, in hormonal male contraception and in transsexuals are discussed. The last chapter describes the role of "investigative" steroid biochemistry applied to tracking anabolic steroid abuse.