The effect of LH and FSH on radiovanadium ("V) metabolism in testis was explored by administering LH and/or FSH daily to hypophysectomized (HYPOX) rats prior to and after 48V injection. Seven and fourteen days after 48V injection, the animals were counted in a whole body gamma counter, sacrificed, and serum and tissue samples taken for weighing and counting. Whole body, serum, and tissue contents of 48V of HYPOX rats were not affected by LH or FSH except in testis. In testis, there were both independent and additive effects of LH and FSH on testicular weight and 48V content, expressed as either content per gram or per organ. LH was more active than FSH. The usual fourfold increase in 48V content per gram seen in HYPOX testis was reduced 50% by LH + FSH. On an organ basis, 48V content was increased 50-100% by LH + FSH compared to either HYPOX or intact rats. These data demonstrate that gonadotropins affect the 48V content of the testes in HYPOX rats in the absence of growth hormone, adrenal steroids, and thyroxine. Whether these data indicate a direct effect of vanadium in reproductive physiology or are secondary to nonspecific trophic or other effects on the testis remain to be determined. 349 0037-9727/80/100349-05$0 1 .OO/O