A general methodology for lifetime performance analysis of existing prestressed concrete girder bridges is presented. Only the superstructure components (slab and girders) are considered. The framework for the methodology is established by identifying four distinct categories: limit state equations, random variables, deterministic parameters, and constant coefficients. The limit state equations are derived by strictly adhering to the load and capacity formulas and requirements set forth in AASHTO specifications. Generality is pursued by establishing parametric limit state equations such that the formulas are applicable to any type of prestressed concrete bridge having similar superstructure components. For time-variant performance analysis, special emphasis is placed on the corrosion penetration modeling in prestressed concrete girders. The developed methodology is applied to seven existing bridges located in Colorado to obtain the lifetime performance of these prestressed concrete girder bridges in the bridge network. Once the values associated with random variables, deterministic parameters, and constant coefficients are assigned, component reliability indices for the slab and the girders are calculated for each bridge. Detailed results are presented for an individual bridge, whereas the lifetime reliability profiles are presented for selected bridges. The focus of the paper is on the formulation and the overall methodology rather than analysis of the results.