The incineration of sewage sludge constitutes an alternative to its recycling in agriculture which has been the subject of increasing opposition on the part of those involved in the farming sector. There are thirty-eight sludge incineration units in France, approximately one-half of them mono combustion units and one-half co combustion units used for domestic waste. In the mono combustion units, used mainly by large authorities, the sludge is initially dried (30%siccity) to enable auto combustion. In co combustion units sludge can be incinerated whatever their siccity. By drying the sludge, the tonnage incinerated is increased, if the incinerator is not saturated by domestic waste. The sludge/refuse ratio reaches 15% for sludge with 20% of siccity. With dry sludge the ratio rises above 20%. Mono combustion produces an output of the order of 330 kg ash per tonne of sludge. It would be feasible to reuse the ash. In co incineration, the ash produced by the burning of sludge consists of 80%-90% slag and 10%-20% residue from the flue gas cleaning. Although the slag has a more heterogeneous composition as a result of the presence of sludge, the management of residue does not pose any particular problem. The cost of solids residue management compared to the overall cost of sludge incineration can be estimated at 16% in mono combustion units and 7% in the case of co combustion. The health risks associated with the incineration of sludge appear to be limited. Emissions of dioxins and furans are lower than with the incineration of domestic waste. Heavy metals are retained in the ash and in the slag. Although the gas phase contains Hg, Cd and a fraction of Zn and Pb, only Hg can be emitted into the atmosphere.