The aim of this study was to determine the effect of coating urea by chitosan at graded levels on ammonia concentration and rumen fermentation in vitro. This study used  Factorial Randomized Complete Block Design (RCBD) to test ammonia parameter and  Randomized Complete Block Design (RCBD) for pH, microbial protein synthesis, dry matter and organic matter digestibility, and Volatile Fatty Acid (VFA). The treatments tested were: P0 = addition non coating urea 1%; P1 = coating urea by chitosan 1%; P2 = coating urea by chitosan 2%; P3 = coating urea by chitosan 3%. The data obtained were analyzed by using  ANOVA and continued with Tukey HSD test with SPSS version 25. The results of this study showed that the coating of urea chitosan had no significant effect on pH, dry matter and organic matter digestibility, microbial protein syntesis, and amonia concentration in the rumen. However, it significantly reduced (P <0.05) total VFA concentration. It can be concluded that the application of urea coating by chitosan does not affect on the degradation of urea in the rumen.