A study was conducted to investigate the effect of fermentation process on the quality changes of broken rice (BR) and rice bran (RB), the two important by-products of the rice industry. The substrates were anaerobically fermented for 72h by adding 2% of baker’s yeast Saccharomyces cerevisiae solution at two different moisture levels (50 and 70%) to make the four treatments: BR -50, BR-70, RB-50 and RB-70. Before and after fermentation, BR and RB were analyzed for proximate components, including dry matter (DM), ash, organic matter (OM), crude protein (CP), ether extract (EE) and crude fiber (CF). The results showed that yeast fermentation of BR and RB was most effective at 48h. It significantly increased the DM, OM and CP of the samples but decreased the ash, EE and CF contents (Pcompared to the value of initial subtrates. Furthermore, fermentation at 50% moisture level for 48h significantly increased (Pto reduce the fat content. In conclusion, fermentation at 50% moisture content for 48h significantly improved the chemical composition of either BR or RB.