Worldwide research on alternative fuels has been intensified due to environmental concern and diminishing of conventional fossil fuels reserves. In Brazil, the usage of fossil fuel for the production of sugar cane has been improved over the years, but there still room for improvements. It is estimated that for 1 ton of processed sugar cane about 2 liters of diesel fuel is used. Over the last year, a fleet of around 110,000 agricultural machines and trucks burned about 1.2 billion liters of diesel. Along with the opportunity of reducing the emission of greenhouse gases there is also an economic advantage of using ethanol because it cost the producer about half the price of the diesel fuel. The reasons above motivated us to develop a diesel-ethanol control for diesel engines using a mechanical diesel injection pumps. An add-on system was developed using an ECM used for passenger vehicles to control engines with either 4 or 6 cylinders. In this system, ethanol is injected into the intake air stream and a pilot injection of diesel is used to achieve ignition. This system was derived from a diesel-CNG system previously developed for urban busses. Careful design of the control algorithms is required to prevent excessive diesel fuel usage and high hydrocarbon emissions. This paper will describe the diesel-ethanol system in detail and present some performance data.