The environmental performance of ethanol production from maize and sugar cane was evaluated. Process simulation was initially conducted using the commercial process simulator Aspen Plus. After mass and energy balances, analysis of the environmental impact was carried out using the waste algorithm reduction (WAR), which evaluates the environmental friendliness of each process. It was found that ethanol production from maize shows a lower potential environmental impact than that from sugar cane. The larger environmental impact of both processes occurs in the aquatic toxicity category, primarily due to high organic charge of the stillage produced.