This study was to investigate the fermentation of rice straw using various microorganisms, i.e., the bacterium Zymomonas mobilis, a distillery yeast Saccharomyces cerevisiae and a co-culture of Zymomonas mobilis and Saccharomyces cerevisiae. Rice straw was pretreated with alkaline and followed by enzymatic hydrolysis using cellulase before fermentation by the bacterium and a distillery yeast. Results show that alkali pretreatment is appropriate for rice straw since this pretreatment condition can produce the maximum cellulose of 88.96% and reducing sugar content of 9.18 g/l. Furthermore, the ethanol yield after enzymatic hydrolysis (expressed as % theoretical yield) was 15.94-19.73% for the bacterium, 20.48-35.70% for yeast and 21.56-29.89% for co-culture. Therefore, the distillery yeast was a suitable microorganism for ethanol production from rice straw.