Seven individual blood samples were prepared consisting of 100 percent male blood, 100 percent female blood, and mixtures of male to female blood in varying ratios. Bloodstains were allowed to air dry for two weeks. In those samples where the blood originated solely from either a male or female, FISH detected only the presence of male or female cells, respectively. FISH accurately identified the presence of male cells in all mixtures; the percentage of detected male cells was comparable to its corresponding dilution factor. 1 table, 1 figure, and 12 references