The aim of this study was to evaluate the effect of oil palm frond treated with ammonia on the carcass weight (CW), rib eye muscle area (REMA) and some meat chemical composition in Bali bull in order to maximal optimization of this oil palm frond. Sixteen Bali bulls, weighing initially between 120 and 140 kg, were randomly divided in to four groups of four animals each. The bulls were placed individually in wooden pens with cement flooring in an open bull barn. The bulls were each randomly assigned in a 60-day experiment. The four treatments included control diet (P0), diet containing 25%, 50% and 75% of ammonia treated OPF for the 2nd, 3rd and 4th, respectively. Randomized Complete Block Design was followed with four treatments and four block of replications applied in this experiment. The results showed that there were no significantly different effect (P>0.05) at treatment on CW, REMA and the meat chemical included water, crude protein (CP), ether extract (EE) and ash content. The findings reffered that, treatment P2, 50 of ammonia oil palm frond (OPF) tend to increase CW, REMA and the meat chemical content of Bali bulls.