Engine vibration characteristics and noise emission of a two stroke spark ignition engine were investigated by using blends of ethanol-gasoline-oil (25% E-70% G-5% O and 50% E-45% G-5% O) and pure gasoline. Engine test conditions were 0.86 kW (5.5 Nm) at 1,500 rpm, 1.25 kW (6.0 Nm) at 2,000 rpm, and 1.83 kW (7.0 Nm) at 2,500 rpm. A high sensitivity electronic vibration analysis system was used for measurement of frequency spectrum of the spark ignition engine vibration. Higher octane number, lower sulphur content, and higher oxygen content were important advantages of blend fuels. Experiment results indicated that when the blend fuels were used, vibration characteristics of the engine changed significantly at 1,500 and 2,500 rpm. In general, in comparison with gasoline, vibration amplitudes and noise emission of the engine with the blend fuels showed a trend of increasing. These results are probably due to oxygen content and higher latent heat of evaporation of ethanol, in which the increasing rate of pressure (dp/dt) and peak pressure values in the cylinder rise during the combustion processes. There was a relation between vibration and noise emissions, due to the increasing trend of them at the same test condition.