Mouse spermatogonial cells can be evaluated for SCE induction after in vivo exposure to chemical mutagens and carcinogens. In this system, cyclophosphamide and ethyl carbamate have been shown to cause significant increases in SCE which, however, tend to be lower in magnitude than those expressed by various somatic tissues. Armenian hamster meiotic chromosomes can be evaluated for normal levels of SCE, and both quantitative and qualitative aspects of crossover exchange. Alternate crossover exchange patterns appear directly related to chiasmata in primary spermatocyte sex bivalents, and also are detectable in sex chromosomes from secondary spermatocytes. Thus, high resolution chromatid exchange analysis is versatile in its application for studies of various forms of normal and abnormal genetic recombination processes in mammalian germ cells.