A modular system for furniture or for exhibition structures, said modular system having wall modules, each comprising - wall surfaces (101, 102) which are situated opposite one another - a front surface and a rear surface which is situated opposite said front surface and - contact areas (103, 104) which are situated opposite one another, that are connected directly to each other and comprising connecting elements (150, 155, 159, 160, 170) for connecting the wall modules to one another, wherein the connecting elements have at least one L-shaped, T-shaped or cruciform cross-sectional area, wherein the wall modules have at least one recess for receiving in each case one portion (150a, 150b, 160a-c, 170a-d) of the connecting element (150, 155, 159, 160, 170) which is matched to the shape of the recess, wherein the recess - runs, starting from the contact area (103, 104) on one side of the wall module, in the direction of the contact area (104, 103), which is situated opposite said contact area, on the other side of the wall module, - passes through the wall module in the direction of a wall surface (101, 102) to the opposite wall surface (102, 101), and - is situated between sections (105a, 106a) of the front surface and rear surface which are situated opposite one another, and wherein further the extent of the portions (150a, 150b, 160a-c, 170a-d) of the connecting elements (150, 155, 159, 160, 170), when they are inserted into the recess in a wall module, in the direction perpendicular to the wall surfaces (101, 102) of the wall module which are situated opposite one another, corresponds to the distance between the wall surfaces (101, 102) of the wall module which are situated opposite one another so that in the assembled state of the item of furniture or exhibition structure, a flat, continuous material surface is present even in the region of the recess, characterized in that a tenon extending in the direction of the direct connection between the contact areas (103, 104) is provided within the recess of the wall module (100,) and in that the connecting element has at least one portion (150a, 150b, 160a-c, 170a-d) with a bore for precisely receiving the tenon. - wall surfaces (101, 102) which are situated opposite one another - a front surface and a rear surface which is situated opposite said front surface and - contact areas (103, 104) which are situated opposite one another, that are connected directly to each other and comprising connecting elements (150, 155, 159, 160, 170) for connecting the wall modules to one another, - runs, starting from the contact area (103, 104) on one side of the wall module, in the direction of the contact area (104, 103), which is situated opposite said contact area, on the other side of the wall module, - passes through the wall module in the direction of a wall surface (101, 102) to the opposite wall surface (102, 101), and - is situated between sections (105a, 106a) of the front surface and rear surface which are situated opposite one another, and wherein further the extent of the portions (150a, 150b, 160a-c, 170a-d) of the connecting elements (150, 155, 159, 160, 170), when they are inserted into the recess in a wall module, in the direction perpendicular to the wall surfaces (101, 102) of the wall module which are situated opposite one another, corresponds to the distance between the wall surfaces (101, 102) of the wall module which are situated opposite one another so that in the assembled state of the item of furniture or exhibition structure, a flat, continuous material surface is present even in the region of the recess,