Single step ethanol production by co-cultures of amylolytic fungus and S. cerevisiase TISTR 5088 was the main purpose of this study. The most effective fungus that could convert starch at high concentrations and gain high reducing sugar content was selected. A morphological study and internal transcribed spacer sequence analysis identified Amylomyces rouxii YTH3 which was submitted to GenBank (accession number KM215272). The fungus rapidly hydrolyzed highly viscous starch at concentrations of 20% and 25% to fermenting sugar at 115.94±0.99 g/l and 159.72±4.08 g/l respectively. In a co-culture system, it was found that starch concentrations and yeast inoculum times influenced ethanol production. Whenever a higher starch concentration was used, the inoculum time should be extended. However, 73.68±1.81 g/l of ethanol from 20% cassava starch medium (theoretical yield 87.46%) was produced when the optimum time of adding the yeast was at 24 h.