The effects of supplementing ruminal bypass amino acid supplement AminoGain® (AG; ADM Alliance Nutrition, Quincy, IL) to steers fed varying dietary energy levels during the growing and finishing phases on growth performance and carcass characteristics was evaluated. Crossbred steers (n = 192; initial BW = 306 ± 26.5 kg) were blocked by BW and assigned randomly to one of six treatments: 0.88 Mcal/kg NEg growing ration and 1.39 Mcal/kg NEg finishing ration, with/without AG (Low/ModAG; Low/ModCTL); 1.17 Mcal/kg NEg growing ration and 1.39 Mcal/kg NEg finishing ration, with/without AG (Mod/ModAG; Mod/ModCTL); 1.34 Mcal/Kg NEg growing ration and 1.59 Mcal/Kg NEg finishing ration, with/without AG (High/HighAG; High/HighCTL). Supplements consisted of 0.45 kg/hd/d of urea-based supplement (CTL) or 0.45 kg/hd/d AG. Growing period final BW was 7 kg heavier for CTL versus AG (P = 0.03); likewise, growing period G:F was 7% greater for control versus AG (P < 0.01). Feed intake tended to increase from d 0-28 for AG (P = 0.07). Low-energy growing treatments had 11% and 15% higher DMI, respectively, than moderate and high-energy growing treatments (P < 0.01); consequently, growing period G:F was greater with increasing dietary energy density (P < 0.01). Ribeye area tended to increase with AG supplementation (P = 0.07). High energy finishing treatments had lower overall DMI and greater overall G:F (P < 0.01). Response to supplementation of AG was not impacted by dietary energy level and did not enhance growth performance or carcass characteristics in this study.