The invention relates to a modular housing system for accommodating electronic circuits, in particular telematics units. Said system comprises at least one basic housing module (10) which has two opposite end faces, wherein on the first end face, a first connecting plate (11) is formed in a first plane and a second connecting plate (12) is formed in a second plane which is different from the first plane; on the second end face, a third connecting plate (13) is formed in the first plane and a fourth connecting plate (14) is formed in the second plane. The first and third connecting plates (11, 13) and the second and fourth connecting plates (12, 14) are respectively formed on the end faces thereof in such a way that a positive engagement can be achieved at least in part, and the first and fourth connecting plates (11, 14) each have at least one opening (0) into which a locking element (60) can be respectively introduced.