Spermatogenesis originates from a constantly renewing population of testicular stem cells (TSCs). The existence of TSCs offers clinically relevant options for preservation and reestablishment of male fertility. Therefore, it is essential to understand the fundamental biology of TSCs and the basic mechanisms of self-renewal, differentiation, and regulation. Although fundamental knowledge of the biology of TSCs is limited, a number of markers have been identified recently. This article reviews the current knowledge of the biology, proliferation, and regulation of TSCs. In addition, new approaches to preserve male fertility are described. TSC transplantation and grafting can be applied to generate spermatozoa from TSCs. These techniques could therefore prove important for fertility restoration in young cancer patients. Based on this exciting research, this review also focuses on current knowledge and future options for cryopreservation, culture, selection, and transfection of TSCs.