Reinforcement method for acrylic sanitary ware products comprising a thermoformed PMMA acrylic sanitary ware product with concave and convex parts, fibre glass, resin and curing agent, which method comprises the following stages: a) covering the face to be reinforced of the thermoformed acrylic sanitary ware product with a set of fibre glass layers, adapting the layers to the form of the face to be reinforced; b) placing on top a bag of elastic material so that both the face to be reinforced and the set of fibre glass layers that cover it can be isolated from the atmosphere by said bag, said bag being provided with means connected to a vacuum apparatus, means connected to the atmosphere and means connected to a supply comprising the resin and the curing agent; c) applying a vacuum between the bag of elastic material and the face of the sanitary ware product to be reinforced so that the set of fibre glass layers adapts to the form of the face of the sanitary ware product to be reinforced; d) opening the means connected to the supply comprising the resin and curing agent, maintaining the vacuum until, by action of the vacuum, gravity and/or injection, the infusion of the resin and curing agent takes place distributing them uniformly through the set of fibre glass layers that cover the face of the sanitary ware product to be reinforced; e) allowing the curing agent to act for the necessary time and, then, removing the bag of elastic material to obtain the thermoformed and reinforced acrylic sanitary ware product; wherein the resin is polyester resin or epoxy resin with fillers and additives, in addition to the curing agent, and is free from thixotropic compounds, and characterized in that the set of fibre glass layers comprises at least three layers in the form of sandwich with the following composition and function: - the first layer or lower layer which is in contact with the face to be reinforced is of woven mat-type fibre glass and has the function of retaining the resin; - the second layer or intermediate layer is of woven mat-type fibre glass fabric or polypropylene, polyethylene or PVC fabric and has the function of distributing the resin to impregnate the layers in contact with it; and - the third layer or outer layer is of fibre glass with biaxial or multiaxial crossed-type mesh fabric and has the function of providing rigidity and resistance to the thermoformed acrylic sanitary ware product. a) covering the face to be reinforced of the thermoformed acrylic sanitary ware product with a set of fibre glass layers, adapting the layers to the form of the face to be reinforced; b) placing on top a bag of elastic material so that both the face to be reinforced and the set of fibre glass layers that cover it can be isolated from the atmosphere by said bag, said bag being provided with means connected to a vacuum apparatus, means connected to the atmosphere and means connected to a supply comprising the resin and the curing agent; c) applying a vacuum between the bag of elastic material and the face of the sanitary ware product to be reinforced so that the set of fibre glass layers adapts to the form of the face of the sanitary ware product to be reinforced; d) opening the means connected to the supply comprising the resin and curing agent, maintaining the vacuum until, by action of the vacuum, gravity and/or injection, the infusion of the resin and curing agent takes place distributing them uniformly through the set of fibre glass layers that cover the face of the sanitary ware product to be reinforced; e) allowing the curing agent to act for the necessary time and, then, removing the bag of elastic material to obtain the thermoformed and reinforced acrylic sanitary ware product; - the first layer or lower layer which is in contact with the face to be reinforced is of woven mat-type fibre glass and has the function of retaining the resin; - the second layer or intermediate layer is of woven mat-type fibre glass fabric or polypropylene, polyethylene or PVC fabric and has the function of distributing the resin to impregnate the layers in contact with it; and - the third layer or outer layer is of fibre glass with biaxial or multiaxial crossed-type mesh fabric and has the function of providing rigidity and resistance to the thermoformed acrylic sanitary ware product.