Selenium, (Se) content of selected tissues and semen and various spermatozoa parameters were evaluated in yearling Angus bulls given supplemental Se. Twenty-four bulls were allotted to two treatment groups: control (n-12) and Se (n-12). Se bulls were given an initial 10ml IM injection containing 50 mg of Se, then injections of 30 mg Se at 21-day intervals for 150 days. Pooled Se concentration (ppm) in serum collected at 21-day intervals averaged .01 and .08 (P < .001) for control and Se bulls, respectively. After 5 months of supplementation, eight bulls in each group were electroejaculated, and semen was processed and frozen for subsequent examination. Bulls were slaughtered for collection of testes, epididymides, seminal vesicles, kidney and liver tissues. Se (ppm) in kidney, liver, seminal vesicle, testis, caput, corpus and cauda epididymis of control and Se-treated bulls was, respectively: .84 and 1.27 (P < .005); .1 and .37 (P < .001); .1 and .21 (P < .001); .35 and .42 (P < .005); .39 and .44; .31 and .34, and .71 and .78. Se (ppm) in extended whole semen, the supernatant fraction and sperm pellet fraction from control and Se-treated bulls was, respectively: .07 and .16 (P < .004); .04 and .13 (P < .001), and .03 and .03. Percentage viability of thawed spermatozoa for control and Se-treated bulls was 26.5 and 23.1, respectively. No differences were observed between control and Se-treated bulls with respect to sperm concentration in the testis and caput, corpus and cauda epididymis. Se treatment of yearling Angus bulls increased the Se concentration of various tissues but had no apparent influence on sperm cell viability, number or Se concentration.