Samples of ram, bull and boar semen were subjected to cold shock and then stained using an indirect immunocytochemical method for detecting acrosin. It was found that the shock treatment abolished staining of the acrosomal region in all but a very few cells. This finding was interpreted as a great loss of proacrosin or acrosin from damaged acrosomes. Using a fluorescent label in the system, sperm cells in both control and treated samples could be scored easily and reproducibly as "stained" or "unstained". Results using a peroxidase label were less satisfactory because staining was not as consistent. Biochemical assessment of sperm acrosin content before and after cold shock confirmed that such treatment caused acrosin loss from the cells into the seminal plasma, but as a quantitative measure of cellular integrity the biochemical method exhibited a number of deficiencies compared with the immunofluorescent cytochemical method. Preliminary data are presented for semen evaluation comparing this latter method with a "live-dead" stain.