Abstract: This study presents the assessment of environmental impact of four stroke petrol engine. The assessment is done by using the Eco indicator 99 method & Eco it software. The assessment of environmental impact of whole life cycle of engine includes the impact assessment of Production phase, Processing phase, transport and packaging phase, use phase, disposal phase of whole life of engine. For assessment, data are collected and then analyzed, during analysis the indicator point obtained from eco it software for particular material and process is taken. After the analysis the impact shows as indicator scores in milli-points, which phase have more indicator score have more impact on environment.