: About 28% of the world energy consumption is utilized for traortation which is directly related to greenhouse gas (GHG) emissions to the atmosphere. Using alcohol-fueled engines is an attractive way to prevent harmful greenhouse gas emissions and global warming effects. Amongst alcoholic fuels, ethanol is the best alternative liquid fuel since it is less toxic and can be produced from abundant renewable resources all around the world. Ethanol is produced biologically from different wastes such as sugary (e.g., sugarcane and sweet sorghum), starchy (e.g., corn and weat), and lignocellulosic waste materials (e.g., agricultural and forestry residues). Sweet sorghum is one of the most promising energy crops for ethanol production. It is also considered as a drought-resistant plant and can be cultivated in temperate, subtropical, and tropical climates. Sweet sorghum stalk is rich in soluble sugars (i.e., sucrose, glucose, and fructose) and insoluble carbohydrates (i.e., cellulose and hemicelluloses), which both can be utilized as raw materials for fermentative ethanol production. As the sweet sorghum stalk harvested, the juice can be extracted and fermented by submerge fermentation. Meanwhile, avoiding the sugar loss, the juice has to be concentrated. However, the juice is very dilute (typically contains 15% sugar) and its concentration (e.g., up to 80%) has a high energy demand. Drying of the fresh stalk is suggested as an alternative to the sugar extraction. The sugars in the stalk can be then converted to ethanol by solid state fermentation. Fungal solid state fermentation (FSSF) of dry sweet sorghum stalk particles (D) for ethanol production was conducted using fungus Mucor indicus and followed by simultaneous saccharification and fermentation (SSF) of the residual bagasse without any pretreatment and addition of fresh micro-organism cells. The effects of important variables including initial fungal inoculation rate (0.001, 1, and 5 g/l), time (24, 48, 72, and 96 h), temperature (28, 32, and 36 ?C), moisture level (65, 75, 80, and 85%), and particle size ( 80, 20-80, and 20 mesh) on the yield of ethanol production by FSSF were investigated. The results showed that M. indicus was able to utilize almost all the glucose and fructose within 48 h, whereas the maximum ethanol yield (0.48 g produced ethanol/g consumed sugars) was achieved by FSSF at 32 ?C, 80% moisture, and particle size of 20-80 mesh with 5 g/l fungal biomass. Moreover, The sweet sorghum bagasse is a lignocellulosic material containing cellulose, hemicellulose, and lignin. simultaneous saccharification and fermentation of the residual bagasse (10, 25, and 50 g/l) was performed at 32, 35, and 37 ?C with different cellulase and ?-glucosidase enzymes loading for 48 h. In the best case, 86% of ethanol yield was achieved when 50 g bagasse/l was saccharified using 15 FPU cellulase and 30 IU ?-glucosidase per gram glucan and simultaneously fermented to ethanol at 37 ?C for 48 h. The results indicated that the fungal solid state fermentation acted as a pretreatment stage and assisted the subsequent simultaneous saccharification and fermentation of the residual bagasse, resulted in up to 4.3-folds improvement in the ethanol production yield. Key Words Ethanol, sweet sorghum, Mucor indicus , solid state fermentation