Suitability of recycled fuels, e.g. packaging wastes and scrap tyres, for combined combustion with other fuels has been studied in the national LIEKKI 2 research programme. The tests have shown that the utilisation of recycled fuels is both technically and environmentally reasonable, and it seems to be suitable solution for the Finnish conditions. About 2.0 million passenger car scrap tyres are formed annually. In addition to these some 130 000 tyres are removed from usage from lorries and different kinds of working machines annually. The total amount exceeds 30 000 tons. The energy content of scrap tyres is high. E.g. the energy content of one passenger car tyre is 31 kJ/kg which corresponds to about 5.0 l of oil. The target of the LIEKKI 2 project is to replace at least 50 % of the fossil fuels used by the Finnish cement industry with alternative fuel up to the year 2000. The effects of the alternative fuels on the process, energy consumption, the environment and the composition and properties of the product are being studied using theoretical modelling, laboratory tests and mill tests in the project started in 1995 at the national LIEKKI 2 research programme. By using recycled fuels it is possible to maintain and to increase the competitiveness of the industry. High process temperatures of the cement industry improve the usability of recycled fuels. The temperature of the material in the combustion zone is about 1450 deg C and the temperature of gases over 2000 deg C. The combustion process is also very homogenous due to large material amounts and flows. E.g. at Parainen the input is about 130 tons of lime- containing raw power in an hour, and the output about 90 tons of cement clinker. The preheating system of the process acts also as a flue gas purification system before the actual purification system. Ash is not formed in the process. The incombustible components react chemically with other material and are bound in the cement clinker