Abstract. An investigation was made to determine the effects of ethanol at ultra-lean effective systems utilizing an experimental study. T he present study is planned to develop and evaluate the performance, emission and combustion characteristics of the ultra-lean burn Internal Combustion engine was modified to operate on ethanol blends fuels. T he study looked at part throttle, constant speed operation of 0%, 10%, and 15% ethanol blends with gasoline mixtures operating in ultra-lean operating systems. In experiment practice the use of homogeneous lean mixtures in engine has been handicapped by several difficulties. T he most serious one is that the flame propagation through mixtures becomes gradually slower as the mixture becomes leaner. T he mixture distribution in a multi-cylinder engine is a problem because even small variation in mixture ratio on the linear side will strongly effect power output. Enhancement of lean combustion of homogeneous mixtures can be achieved by (i) using ethanol blends with gasoline (ii) using high-ignition energy (iii) providing high compression ratios (iv) creating high swirl in the combustion chamber.