Fully developed low-Reynolds-number turbulent ¯ow through straight permeable pipes with circular cross-section is investigated by means of direct numerical simulation. Three dierent cases of wall permeability are treated and compared with the case of a solid wall. In two of these cases, the wall satis®es the no-slip condition, but allows for the wall normal velocity ¯uctuations in two dierent ways. In the third case, the pipe wall has rectangular openings of size 6Dz  10RDu , regularly distributed over the whole surface, similar to a chessboard, where the white areas represent the openings and the black ones the solid wall. Velocity boundary conditions in the openings are such that the mean mass ¯ux across the wall is zero and the ¯ow in the openings is stressfree. All ¯ows are driven by the same mean pressure gradient. Consequently, those ¯ows which satisfy the no-slip condition have the same wall shear stress and hence the same turbulence Reynolds number Re s 360. Pipe ¯ow with wall openings exhibits a small, but ®nite Reynolds shear stress at the wall. If the friction velocity is de®ned via the total stress at this wall, the ¯ow nominally has the same turbulence Reynolds number. The overall eect of a permeable wall with rectangular openings is a mean axial slip velocity at the wall and reduced viscous stress. In a thin near-wall layer of thickness mau s , the turbulence activity is increased compared to the ¯ow cases, where the velocity components satisfy the no-slip condition. All three rms-velocity ¯uctuations are non-zero. As a result the structure of the Reynolds stress tensor is modi®ed in this region. This is also re¯ected in higher order central moments of the velocity ¯uctuations. A permeable wall with rectangular openings may be viewed as a model for a rough wall with a mean non-dimensional roughness height of 8.3 wall units. Close to such a wall the budgets of the Reynolds stress tensor dier strongly from those for ¯ow along a smooth impermeable wall.