The conservation of mural paintings requires a deep knowledge of the alterations caused by natural ageing, environmental agents and previous restoration treatments. All the operations concerning cleaning and consolidation of wall paintings must assure the safety of the paint layers. This is especially true the more fragile the painting technique. For example, “a secco” paintings, executed with organic binders such as tempera, oil, glue, when altered and damaged, present a very weak adhesion to the mortar underneath, and provoke detachment of paint fragments. In this circumstance it is necessary to find a feasible alternative to the usual cleaning methods (wet and mechanical ones) and a valid way to operate. Moreover, the removal of scialbo layers (a thick, pure lime layer applied on the wall painting) presents difficulties in order to preserve the integrity of the painting layers. Previous experiments carried out in Opificio with Er:YAG laser on easel painting cleaning, lead us to extend the experiments on the cleaning of mural paintings. This program is intended to establish parameters, such as emitted wavelength, fluency and associated energy, applied on mural paintings. The first step was to verify the upper limits of energy for a large set of laboratory samples, prepared following the traditional techniques of mural paintings. Then experiments were carried out on the following mural paintings: a Giotto school fresco, located in the Bargello Palace in Florence, which presents areas with scialbo and secco painting, and a sixteenth century mural painting in the Boiardo’s fortress in Scandiano (RE). The analyses were performed by using optical microscopy, SEM, FTIR, and GC-MS techniques. This paper reports and documents the most significant results obtained during the experiments.