The knowledge of the material properties of existing metal bridges is essential for the resistance assessment and the determination of the remaining lifetime of the bridge. For old metal bridges, that were built between 1870 and 1940 in particular, the material parameters are in many cases not available. Yet, especially the old bridges require more exact and efficient assessment methods that call for a precise description of the material. This section focuses on the material of old metal bridges. The required material properties can be obtained using different methods: - Application of reference values for material parameters that are taken from literature. - Application of material properties that are described as statistical parameters, if a sufficient data base is available. - Determination of material properties using an individual analysis by testing. The direct analysis of material properties provides the most exact and bridge-specific information. Yet it is only recommended where literature values or statistically derived material models lead to a too conservative assessment. The most important material parameters to assess the resistance of a structure towards design loads and environmental actions during the structure's lifetime are strength and toughness. Concerning durability and strengthening matters also aspects as workability (e.g. weldability) and resistance against corrosion effects are relevant. In the following the essential parameters are shortly defined: - Chemical analysis. - Strength properties under static loading and fatigue properties. - Toughness properties. - Fracture mechanical properties (fracture toughness and crack growth parameters)