This experiment was conducted to study the effect of the supplementation of urea to the raw rice straw and the lime treated straw on the utilization of protein and crude fiber. The results obtained from native goats are summarized as follows: (1) The body weight of animals was uniformly decreased throughout the experimental period. The rate of feed consumption was much higher for the animals fed lime treated rice straw than for the animals fed raw rice straw. The amount of excreted feces and urine was not affected either by the treatment of lime addition or urea. (2) The average pH of rumen juice(7.6) in the animals fed by lime treated rice straw with or without supplementation of urea was higher than the animals fed by raw rice straw. It is apparent that formation of calcium carbonate would cause the rise in pH, since increased production of calcium carbonate would be resulted from the addition of lime by the following reaction; Ca(OH2)+CO2→CaCO3+H2O The number of bacteria and protozoa in the rumen of animals fed lime treated rice straw was much higher than control group. (3) It is also observed that the animals fed lime treated rice straw excreted considerably less amount of nitrogen in the urine. The digestibility of protein was significantly (P<0.01) improved by the supplementation of urea to the lime treated rice raw. However, no difference in the digestibility of N.F.E and energy of the ration, although the digestibility of crude fiber was slightly improved by treating the rice straw with lime. (4) The digestible nutrients, T.D.N. and starch value of raw rice straw, lime treated rice straw, and urea were calculated.