This study looks at the impact on selected toxic exhaust gas components in a compression ignition engine supplied with diesel-fuel emulsion. During the empirical research, a turbocharged PERKINS 1104C-E44T diesel engine was supplied with water-fuel emulsion where water content in the mixture was 15% by volume and diesel fuel. The tests were performed with load characteristics at two speeds of the engine crankshaft at maximum torque speed of 1,400 rev/min and maximum engine power speed of 2,200 rev/min. At each operating point of the engine concentrations of toxic exhaust gases we recorded carbon monoxide CO, hydrocarbons HC, nitrogen oxides NO_x, and particulate matter PM. On the basis of results and calculations, specific emissions of toxic substances in accordance with ISO 8178 were designated.