Among the methodologies which consent to evaluate and compare the environmental sustainability of processes and complex systems of whatever nature, Life Cycle Assessment (LCA) is one of the tools which has been applied the most in these past years, for example in defining integrated management strategies for municipal solid waste. LCA is an objective method for evaluating and quantifying the energy and environmental loads and the potential impacts associated with a product/process/activity during its entire life cycle ("from cradle to grave"), i.e. from the acquisition of the raw materials to the disposal of by-products. The activities which have been carried out up to today on this theme have aimed at the evaluation and comparison of the environmental loads related to specific production or waste treatment processes. In particular, LCA has been applied to identify the most critical processes from an environmental perspective related to the methods applied for olive oil manufacturing in southern Italian regions and the treatment strategies applied at present for the management of residual waste from separate collection in the province of Rome. Such studies aim at identifying, through the quantification for each unit process of materials and energy consumption and of the emissions caused in different environmental compartments, the environmental criticalities connected with the process under examination and to evaluate improvement solutions aimed at the reduction of specific impacts and at the optimization of energy and material use.