In this study the structural response of post-tensioned structural glass beams is investigated. This is done through four-point bending tests on two series of post-tensioned glass beam specimens. The beams consist of three layers of annealed float glass and are posttensioned by means of two stainless steel tendons positioned along the upper and lower edge of the beams. In addition, a series of reference beams, with identical geometry but without tendons, is tested. From the results it is concluded that post-tensioning a glass beam is a feasible concept, which provides the beams enhanced initial breakage strength and enhanced post-breakage performance. More specifically, the post-tensioned beams reach up to 80% higher initial breakage loads than the reference beams. Furthermore the post-tensioned glass beams reach postbreakage load levels up to 200% of their initial glass breakage load and demonstrate highly ductile post-breakage response. Further studies will focus in more detail on this promising concept of post-tensioning glass beams.