The conformations of 3-pyridinoyl indoles, which are intermediates 5-fluoropentyl-3-pyridinoyl indole, were investigated using their X-ray crystal structures. All derivatives existed as s-trans conformers. A pseudo-planar conformation was observed in the 2'-yl isomer of 3-pyridinoyl indoles. On the other hand, twisted conformations were observed in 3-pyridinoyl 2-methylindoles. The conformations of