An experiment was carried out to study to the role of urea lime mixture in concentrate containing cassava on the rumen fermentation of the etawah crossbred goat through in-vivo experiment. A randomized block design (RBD) consisted of 4 different rations and 4 replicates was used in this experiment. Atotal of 16 etawah crossbred goats with initial body weight ranging from 12.4 - 19 kg were aranged in to 16 pens experiment. Four feed treatments (A, B, C and D) were offered to four groups of four goats. The first treatment (A) was 50% elephant grass 50% concentrate (without cassava urea lime) as control diet, the second treatment (B) was 50% elephant grass 50% concentrate (without cassava, with 4% urea and 2% lime), the third treatment (C) was 50% elephant grass 50% concentrate (with 25% cassava, 4% urea and 2% lime), and fourth treatment (D) was 50% elephant grass 50% concentrate (with 50% cassava, 4% urea and 2% lime). Ration was composed based on standard requirement of 15 kg body weight goat with 75 g daily weight gain. Results of This study showed that the concentration of NH3, VFA, propionic acid, and protozoa rumen population on treatment A, B, C, and D were significantly different (p<0,05). It can be concluded that Utilization of 4% urea and 2% lime without cassava in concentrate increased N-NH3 level of rumen fluid, but level of N-NH3 rumen fluid on goat fed with 4% urea and 2% lime in concentrate contain 25 and 50% cassava was not increase, compared to thoset fed controled (treatment A). Propionic acid level and rumen protozoa population could be increased through urea lime and cassava addition in concentrate.