We investigated rice husk as the sole carbon source as well as biofilm carrier in the biological denitrification of wastewater in up-flow laboratory reactors. Fast startup of the reactor and high nitrate removal efficiency was observed. The highest denitrification rate (about 0.096kg/m³·d) was achieved when flow rate and nitrate concentration were 41.4L/d and 25.0mg/L, respectively. Flow rate and nitrate concentration of the influent were observed to have a significant effect on nitrate removal efficiency. The reactor had the ability to accommodate a wide range of pH (6.5-8.5) and DO (1.5-4mg/L). A time-dependent decrease in nitrate removal efficiency was observed after 72 days of operation. And the addition of new rice husk brought about a rapid increase of nitrate removal efficiency. Results showed that rice husks can be an economical and effective carbon source for the nitrate removal process.