Rice bran as one of the source of phosphorous for the monogastric animals has the highest levels of phytate. The inability of poultry to utilize phytate P necessitates the dietary addition of inorganic P; this adds to increased feed costs, increases P excretion, and creates an environmental contaminant By the way, phytate phosphorous has been considered to be absorbed easily in ruminant because of microbial phytase degradation in the rumen. This study would try to use rumen liquor as starter for fermentation processing of rice bran. The aim of this study is to evaluate the activity of phytase on the fermented rice bran. Factorial model based on completely (block) randomised design was employed through out the experiment. Two factors have been evaluated (i) the level of rumen liquor's addition (15; 30 and 45%), and (ii) the length of fermentation (0;2;4; and 6 days). Data were subjected to ANOVA using the general models procedure of SAS. Duncan and Orthogonal test was used for further analysis. The results indicated the interaction between these two factors. Maximal activity of phytase was reached on the addition of 30% rumen liquor to the rice bran within 2 days of fermentation process. A longer incubation period would give no further effects to the phytase activity and phytate phosphorus degradation.