Abstract: The invention is based on a multi-chamber flat tube (V1-V17) having at least two chambers (1, 2) for holding the flow of a fluid, produced by deforming a sheet-metal strip, in particular produced in a bending and/or folding and/or crimping process, in which a closed profile is formed by: opposite wide walls (4, 6) which are connected to one another by means of opposite narrow walls (5, 7) which form in each case one deformed region, with the wide and narrow walls forming outer sides of the profile, with a first wide wall (4) being formed by an inner section of the sheet-metal strip which is situated between side sections of the sheet-metal strip, and with a second wide wall (6) being formed by side sections, which are arranged to the sides of the inner section, of the sheet-metal strip, with the first and second wide walls (4, 6) being connected by means of a web (3) which separates at least two chambers and which forms an inner side of the profile and which is formed by an edge section (3A, 3B) of at least o