Diesel has been used extensively as fuel for small agricultural engines in India. As natural gas is available in abundance, lot of interest is shown to substitute gas for diesel in these engines either partially or fully.Natural gas has a high Octane rating and hence to replace diesel fully, major irreversible changes in the diesel engine is required. However, in the dual fuel (diesel + gas) system a large percentage of diesel substitution is possible by the addition of the components of the conversion system. A simple dual fuel system has been developed indigenously for this study.Engine tests with dual fuel gas system have been conducted on a single cylinder diesel engine. These results show that the performance of the engine with dual fuel system can almost match that of standard diesel engine.