This study was conducted due to the necessity for improving the processability of commingled yarns during textile processing, in particular dense 3D preform weaving. Open structure of the commingled yarns caused higher production stops. As a possible solution, GF/PP commingled yarns with different twisting levels were produced. Effect of twisting on the mechanical properties of commingled yarns and on their compression molded UD composites are determined. Further tests were executed about yarn/yarn and yarn/metal friction of twisted commingled yarns, which are important properties during textile processing. Theoretical approaches such as a yarn model with linear bar elements and lamina equation with an equivalent angle distortion of over-delivery proved useful to relate the structural parameters and mechanical properties. As a result, twisting did not significantly affect the modulus of elasticity of UD-composites, however, the tensile strength of UD-composites were reduced by further processing even without twisting. Therefore, small twisting levels can be applied on commingled yarns to improve processability of dense preforms without significantly affecting the mechanical performance. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 246-256, 2012