Summary. Glycerolated semen specimens of several donors were examined for DNA content after refrigeration at +6\s=deg\C for 7 days, and after storage in liquid nitrogen for periods ranging from 2 to 75 weeks. Fresh specimens were also studied. DNA determinations were made in each case by both Feulgen microspectrophotometry (in arbitrary units) and by the Webb-Levy chemical determination. The quantity of DNA per cell in arbitrary units and in mg \m=x\10\m=-\9remained constant after refrigeration, and after freezing-preservation for all time periods studied. Discrepancies between the two kinds of determination, and the concept of embryonic mortality due to aged spermatozoa are discussed.