This experiment was conducted to study the effects of supplementation of dried leucaena leaf (LL) at levels of 0,300 and 600 g/hd/d (air-dried) on the growth performance of native cattle receiving either untreated rice straw (RS) or urea-treated rice straw (UTR) based diets. Eighteen native bull calves and 18 native heifer calves with initial weights of 95.5 + 15.7 kg were randomly assigned to a 2 x 3 factorial arrangement in a randomized complete block design (RCBD). Six diets were given as follows: 1) Untreated rice straw (RS); 2) RS + 300 g LL/hd/d; 3) RS + 600 g LL/hd/d; 4) Urea treated rice straw (UTR) (5%,w/w); 5) UTR + 300 g LL/hd/d and 6) UTR + 600 g LL/hd/d.