A study was conducted to determine the effect of an exogenous enzyme treatment on various production and carcass characteristics of growing and finishing steers. In the 84-day growing trial, 32 primarily British crossbred individually fed steers (259 kg BW) were randomly assigned control (C) or enzyme (E) treated diets (n=16 for C and E). The diet contained 65:35 (DM basis) forage:concentrate. Steers on the enzyme treated diet received a total mixed ration (TMR) that contained a solution with endoglucanase and xylanase activity at a rate of 5580 and 15,880 IU/kg of TMR DM, respectively. Average daily gain (ADG), dry matter intake (DMI) and feed efficiency (FE) were not affected by treatment (P>0.05), although FE showed a trend for improvement during the first 28 days for the enzyme treatment (P=0.063). The finishing trial consisted of 20 individually fed steers (409 kg BW) randomly assigned treatment (n=10 for C and E) in an 84-day trial. Steers on the enzyme treated diet received the same enzyme solution and level as in the growing trial. The finishing ration consisted of a 20:80 forage:concentrate ratio (DM basis). Results indicated no difference (P>0.05) for ADG, DMI or FE as well as various carcass traits including hot carcass weight, ribeye area, backfat, yield, quality grade or cutability. It is concluded from these growing and finishing trials that the enzyme concentrate used did not affect production or carcass characteristics, but may be beneficial for improving feed efficiency when cattle are first placed on feed.