The present invention provides a process of lost wax microcasting with recycling of exhausted wax in order to reduce disposal costs, without compromising the quality of the production of the final components. The process can be used in place of the less valuable wax type, or in place of the wax used for the realization of the clusters and accessories. The proposed process is simple, safe and reliable with low costs. The process comprises the following steps: molding of one or more wax models, identical to the end pieces to produce, using a first formulation of wax; molding of one or more molds of sprues (connecting passages), using a second formulation of wax; assembling of said one or more models and said one or more molds of sprues, to form a cluster; coating of said cluster with a ceramic shell; removing of wax from said shell; treating of said shell in an oven; casting of molten metal alloy within said shell and subsequent cooling to obtain a solidified casting; cracking of the shell to release the solidified casting; removing of the sprues and finishing of the pieces; and characterised in that it additionally comprises the following steps: melting of the exhausted wax coming from said step of removing wax from said shell, to obtain a molten exhausted wax; removing of water from said molten exhausted wax, to obtain de-hydrated molten exhausted wax; removing of ceramic residues, ashes or other impurity by filtration of said de-hydrated molten exhausted wax, to obtain recycled wax; adding virgin wax in a quantity equal to at least 30% by weight of the total of the recycled wax, and at least equal to the amount of recycled wax in the case in which the same has been already obtained following a process of lost wax micro casting in which a wax formulation that contain recycled wax was used, to obtain said second formulation of wax; delivering of said second formulation of wax to said molding of one or more molds of sprues. Preferably, said step of removing ceramic residues, ashes or other impurity by filtration is such as to reduce the ash content down to a level not higher than 0.05% by weight of the total of said second formulation of wax. Optionally, after or simultaneously with said step of adding virgin wax, a dye is also added, preferably in an amount lower than 0.01% by weight of the total of said second formulation of wax. More preferably, said second formulation of wax is characterised by having the following properties: freezing point: 58-64°C; melting point (drop melt point): 65-71°C; ash content: 0.05% by weight; penetration: 8-14 dmm; viscosity at 70 °C: 0.6-1.3 Pa·s.