Ractopamine hydrochloride (RAC) is fed to cattle before slaughter to improve growth performance and carcass lean meat yield. Zinc (Zn) is required for RAC function; however, Zn level and source required to optimize RAC response is unknown. The objective of this research was to evaluate the response of Zn provided as an amino acid complex (Zn-AAC) on growth, feed efficiency, and carcass merit in growing-finishing beef steers. Two well-controlled studies were conducted at commercial feedlot research facilities in TX and OK. At the TX and OK sites, 3,849 (initial BW = 344 ± 2.3 kg) and 2,105 (initial BW = 311 ± 3.5 kg) steers, respectively, were randomized across 8 pens/treatment. Common treatments at each site were: (1) Control (CON) = basal diet with no Zn-AAC or no RAC;(2) RAC = 320 mg RAC·hd⁻¹·d⁻¹(TX) and 200 mg RAC·hd⁻¹·d⁻¹(OK);(3) Zn-AAC + RAC = RAC plus 360 mg Zn-AAC·hd⁻¹·d⁻¹. At both sites, RAC was fed for the final 28-d before slaughter. Basal diets provided steam-flaked corn as the primary grain source. Total dietary Zn concentration in CON diets was 62 and 76 mg Zn·kg⁻¹DM for OK and TX, respectively. Individual and combined study analyses were conducted using SAS on growth performance and carcass data. Pen was the experimental unit. Combined study analyses indicated RAC increased carcass-adjusted final BW (P ≤ 0.02), ADG (P ≤ 0.01, feed efficiency (P ≤ 0.01), HCW (P ≤ 0.03) and ribeye area (P ≤ 0.01) compared with CON. Adding Zn-AAC to RAC produced additional improvements in carcass-adjusted final BW (P ≤ 0.09); ADG (P ≤ 0.01 and HCW (P ≤ 0.11). Marbling score, back fat thickness and calculated yield grade were not affected by treatment. Incidence and severity of liver abscesses were reduced (P ≤ 0.02) with Zn-AAC + RAC compared with CON and RAC. Feeding Zn-AAC to cattle fed RAC produced additional improvements in growth and carcass yield and reduced prevalence of total and severe (A⁺) liver abscesses.