The paper deals with the complex process of restoration of the Baroque house sign of the „Red Crayfish” from the collections of the Prague City Museum. The work was originally a shop sign of a Prague merchant and later a house sign. It is made of plaster with metal reinforcement. It was in a fragmentary state – broken into several parts and fragments. The inner supporting structure was damaged by corrosion. The surface was heavily soiled and cracked. The aim of the restoration intervention was to ensure the stability of the entire work, to prevent further degradation and to carry out its overall visual reconstruction. The paper describes results of the material survey using optical microscopy, individual steps of the restoration process including surface cleaning, removal of secondary supplements and inappropriate interventions, restoration of the supporting structure, strengthening, surface treatment and completion of the work. This study is also a summary of the conclusions of the author's diploma thesis accomplished in the studio of sculpture restoration at the Academy of Fine Arts in Prague.