It is presented a finite element so lution on basis of an extended one-dimensional cross-sectionelement to the calculation of the warping function, the torsional properties and the shear stresses, dependent on it, for thin-walled prismatic beams under Saint-Venant torsion. The formulated finite two-node-element with six element degrees of freedom can capture through inclusion of the torsion around the element axis the linear term of the variance of warping function perpendicular to the element axis. Only the shear stresses of the ring shear flows in the closed section parts unchangeable over the wall thickness can be calculated with the simple two-node-element with two element degrees of freedom. The extended two-node-element supplies in addition also the shear stresses of the cut open cross-section linearly changeable over the wall thickness. © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.