The pulsed jet millimeter wave spectra of five isotopomers of the weakly bonded oxirane...Xe complex have been measured. Information on the equilibrium conformation, dynamics and dissociation energy have been deduced. The equilibrium distance of Xe with respect to the center-of-mass of the molecules is 3.82 Angstrom, with Xe tilted 15degrees from the perpendicular to the center-of-mass of the ring toward the oxygen atom. The dissociation energy is estimated, from the centrifugal distortion constant D-J, to be approximate to3.9 kJ/mol.