Two different molecules that are mirror images of each other, so-called enantiomers, can possess very different functional properties in biological systems or as pharmaceuticals. For this reason, separation and analysis of enantiomers is of great importance. We demonstrate that different enantiomers are transported typically at different velocities in a fluid streaming through a straight microchannel. As underlying mechanism we identify a translation-rotation coupling in the motion of the molecules which is specific for the molecule structure. The possibilities to exploit this effect for the separation of enantiomers are briefly addressed.