With the recognition that the engineering structures maintenance and repair needs far exceed the rescourses available to adress these needs, many firms have to turned to the development of ESMS (Enginnering Structures Management System) as a method to improve the allocation of these limited resources and the condition of their engineering structures. The ESMS is based on performance modelingbecause of without the actual condition of the structures and the future deterioration process any model could not be build up. The paper provides an overviev of the need for ESMS and the posibble description of the performance modeling. © 2005 IEEE.