Abstract: The present invention relates to a construction system (1) comprising construction elements (2) which exhibit a number of transcurrent holes (8) distributed along the aforementioned elements, connecting pieces (3) and locking devices (4) interacting with them for the purpose of connecting construction elements to one another. The aforementioned connecting pieces (3) consist of at least two threaded (5) connecting uprights (6, 7) projecting from a common connecting frame (9) which exhibit a form corresponding to the holes (8) in the construction elements, and threaded (11) connecting hats are so arranged, when screwed onto the aforementioned connecting uprights, as to clamp assembled construction elements (2) securely to an abutment (12) on the connecting piece (3) in question.