A sensitivity analysis of the effects of the operating hours scheduling of MSW incinerators is not common in the literature. To this concern, the present paper wants to give a contribution to the understanding of these effects in order to add a new point of view beyond the analyses based on overall balances. The selected case study concerns a plant proposed for a region in the North East of Italy. A characteristics of the selected case study is the long period of non-operation of each RMSW treatment line (3 months per year). A critical analysis of the effects of maintenance stop fractionation, of maintenance stop lasting on yearly basis, of maintenance stop seasonal scheduling, also at device level is presented. Considering the extreme scenarios of seasonal stop, a reduction of up to 20% around could be obtained. In case of more usual periods of stop for maintenance this value would be lower.