Bioethanol produced from sugarcane is anticipated to make a major input on transportation fuel markets. In this paper, the environmental effects of bioethanol-gasoline blends were evaluated in use a spark ignition (SI) engine. The bioethanol used in this study was produced by a sugar refinery in Turkey. To determine the exhaust emissions of bioethanol and gasoline blends, SI engine operated at different engine test conditions, and also the test results of bioethanol-gasoline blends compared with those of pure gasoline. The experimental results showed that when the test engine was fueled with bioethanol-gasoline blends, CO and unburned HC emissions decreased, but CO2 and NOx emissions increased. At the same time, the results indicated that the air-fuel equivalence ratio increased with the increase of bioethanol percentages in fuel blends.