Sixteen animals were used to examine intramuscular implantation of 200 mg testosterone to steers which were fed in pens on one of two planes of nutrition. During the fifty-six days after first implantation body mass gains were 0.88 and 0.78 kg/d on the higher plane of nutrition, and 0.35 and 0.47 kg/d on the lower plane for implanted and control steers, respectively. Animals were re-implanted with 200 mg testosterone 196 days after the first implantation. After the second implantation until slaughter 77 days later (when animals were 29 -31 months old) implanted and control animals respectively showed gains in body mass of 1.14 and 1.02 kg/d on the higher plane and 0.78 and 0.88 kg/d on the lower plane of nutrition. On the higher plane of nutrition implantation led to greater efficiency of feed conversion and growth rates and resulted in heavier carcasses with greater eye-muscle measurements but thinner back fat. On the lower plane, implantation led to a decrease in thickness of back fat. These results emphasize the importance of an adequate plane of nutrition for a growth response by steer to androgens.