(E) geometricisomers of 2-(2-phenylbenzylidene)-3-quinuclidinone were solved by direct methods, using diffractometric data, and refined to final R values of 0.040 and 0.061. The molecules of the (Z) and (E) geometricisomers show trans and cis conformation of the substituents around the double bond, respectively. The quinuclidine and the diphenyl moieties show deformations in their geometric and conformational