Maintenance costs of high-speed lines in Europe-a subject rarely addressed in technical literature-are analyzed. The design characteristics of each line and of the traffic supported by these lines are discussed. A new classification specific for these types of lines is proposed to study the deterioration of various elements and the cost for conservation. This classification is based on the typology of the rolling stock instead of the product that it transports (passengers or freight). The structures adopted by the infrastructure managers to carry out the maintenance operations are also discussed. Moreover, numerical specific data on the maintenance cost of a kilometer of track per year, for a line on which only high-speed trains circulate, are presented. The influence of mixed traffic is analyzed, and the economical costs for the maintenance required for these lines are also quantified.