In the present paper a procedure is shown on the basis of the finite element method with which for arbitrary thin-walled cross-sections the warping function and the torsional properties, dependent on it, relevant with spatial beams can be determined. In this case it does not play any role, whether the cross-section shows an open, a closed or a mixed open-closed structure. By means of an example with a mixed open-closed cross-section with only a single cell a numerical comparison is carried out between the results of a finite element analysis with simple line elements and those of more precise plane elements. A further example contributes to the verification of the procedure for cross-sections with more than one closed cell. © 2005, VDI Fachmedien GmBbH & Co.. All rights reserved.