A method and apparatus for determining the quantities of pollutants in the exhaust gases of internal combustion engines wherein an essentially constant and fully conditioned quantity of humidity and/or temperature-conditioned combustion gas is supplied to the internal combustion engine at each instant whose quantity corresponds to at least the maximum quantity required by the respective combustion engine, wherein the exhaust gas is diluted with the quantity of combustion gas not used by the combustion engine, and then tested relative to quantities of pollutants and flow rate.