(Chemical equation presented). Remarkably high specific rotations, even at 589 nm, are exhibited by the enantiomerically pure σ-[9]helicenes (M)-(-)- and (P)-(+)-[9]triangulanes (see scheme). This significant power of rotation, which is in very good agreement with calculated values, must be attributed to the rigid helical framework of σ bonds in these formally saturated hydrocarbons.