An integrated process for full utilization of rice straw components was proposed. Separating different components of the rice straw according to their chemical properties is the key for complete and efficient utilization of rice straw. Pretreatment with dilute acid resulted in decomposition of 70.3% of the original hemicellulose in rice straw. The obtained hydrolysates were fermented to ethanol by three pentose fermenting strains, and Pichia stipitis CBS 6054 was shown to be the most preferable strain for bioconversion. Following the dilute acid pretreatment, delignification of the residual materials was performed with sulfomethylation reagents, and nearly pure cellulose was obtained. Analysis of the cellulose component showed that hydrolysis proceeded fast and with high yields.