Modularly assemblable furniture system for assembling box-shaped furniture systems such as a set of shelves, comprising: - a number of first boards (2, 2',2",2"') with a thickness and a first lateral face and a second lateral face and a first edge face and a second edge face, - a number of second boards (3, 3', 3") with a thickness and with a first lateral face and a second lateral face and a first edge face and a second edge face, as well as - a number of angle brackets for a rectangular assembly of a first board (2, 2', 2",2"') with a second board (3, 3', 3"), where the angle bracket comprises: - a board-shaped basis part with a first basis part face and a second basis part face, - a first projection comprising two dowels (32, 33) projecting from the first basis part face, and - a second projection comprising two dowels (32, 33) projecting from the second basis part face, said projections being positioned at a distance ( a) from each other, - said second boards (3, 3', 3") being provided with, in relation to the thickness, centrally positioned edge recesses (17, 17') in a couple of opposing edge faces (15, 16), said edge recesses (17, 17') being dimensioned for reception of the second projections, and - said first boards (2, 2', 2",2"') having in the first lateral face first and second face recesses (12.1-12.4, 12.1'-12.4'), which are dimensioned for reception of the first projection of the angle bracket, said face recesses (12.1-12.4, 12.1'-12.4') being positioned at a distance from the first and the second edge faces (13, 14), respectively, so that when the second projections of the angle bracket are engaged with the edge recesses (17, 17') of a second board (3, 3', 3"), said edge face (13, 14) of the first board (2, 2', 2",2"') is flush with the lateral face (7, 8) of the second board (3,3',3") so that an end wall of said furniture system appears essentially as a plane surface, wherein the face recesses (12.1-12.4, 12.1'-12.4'12) on the first and second lateral face (5, 6), respectively, of the first boards (2, 2', 2",2"') are positioned two by two opposite each other perpendicular on the lateral face (5, 6) when seen in a sectional view, and in that the modularly assemblable furniture system is for assembling box-shaped furniture systems without use of other fixtures, such as nails or screws, to hold the system together. - a number of first boards (2, 2',2",2"') with a thickness and a first lateral face and a second lateral face and a first edge face and a second edge face, - a number of second boards (3, 3', 3") with a thickness and with a first lateral face and a second lateral face and a first edge face and a second edge face, as well as - a number of angle brackets for a rectangular assembly of a first board (2, 2', 2",2"') with a second board (3, 3', 3"), where the angle bracket comprises: - a board-shaped basis part with a first basis part face and a second basis part face, - a first projection comprising two dowels (32, 33) projecting from the first basis part face, and - a second projection comprising two dowels (32, 33) projecting from the second basis part face, said projections being positioned at a distance ( a) from each other, - a board-shaped basis part with a first basis part face and a second basis part face, - a first projection comprising two dowels (32, 33) projecting from the first basis part face, and - a second projection comprising two dowels (32, 33) projecting from the second basis part face, said projections being positioned at a distance ( a) from each other, - said second boards (3, 3', 3") being provided with, in relation to the thickness, centrally positioned edge recesses (17, 17') in a couple of opposing edge faces (15, 16), said edge recesses (17, 17') being dimensioned for reception of the second projections, and - said first boards (2, 2', 2",2"') having in the first lateral face first and second face recesses (12.1-12.4, 12.1'-12.4'), which are dimensioned for reception of the first projection of the angle bracket, said face recesses (12.1-12.4, 12.1'-12.4') being positioned at a distance from the first and the second edge faces (13, 14), respectively, so that when the second projections of the angle bracket are engaged with the edge recesses (17, 17') of a second board (3, 3', 3"), said edge face (13, 14) of the first board (2, 2', 2",2"') is flush with the lateral face (7, 8) of the second board (3,3',3") so that an end wall of said furniture system appears essentially as a plane surface, wherein the face recesses (12.1-12.4, 12.1'-12.4'12) on the first and second lateral face (5, 6), respectively, of the first boards (2, 2', 2",2"') are positioned two by two opposite each other perpendicular on the lateral face (5, 6) when seen in a sectional view, and in that the modularly assemblable furniture system is for assembling box-shaped furniture systems without use of other fixtures, such as nails or screws, to hold the system together.