For many structural glass components, buckling is known to be a major design issue, which is influenced significantly by several parameters. The latter include boundary conditions, slenderness and geometrical imperfections, in particular initial curvatures. However, in spite of their importance for building practice, experimental data for the latter are very poorly documented. Consequently, an extended experimental campaign is presented in which initial curvatures of 312 monolithic and laminated glass beams with a variable length, height, glass thickness, glass type and - wherever applicable - interlayer, have been accurately measured and analysed. Major conclusions have been drawn regarding the shape and the size of initial curvatures. (C) 2010 Elsevier Ltd. All rights reserved.