Total cross sections (TCSs) for electron and positron scattering from chlorobezene (C6H5Cl) and chloropentafluorobenzene (C6F5Cl) molecules have been measured by using the linear transmission time-of-flight method. The impact energies are from 0.4 eV to 1000 eV and 0.2 to 1000 eV for positron and electron impacts, respectively, for scattering from C6H5Cl molecules, and 0.8 eV to 600 eV for electron and 0.4 to 600 eV for positron scattering from C6F5Cl molecules. Two resonance structures are observed in the C6H5Cl electron TCSs at 0.8 eV and 2.5 eV, which merge to the single resonance at 1.6 eV of the C6H6 molecule. This is an evidence of the splitting of the degenerate e(2u) orbital of the C6H6 molecule into two upon substitution of an H atom by the Cl atom. C6F5Cl electron TCSs are lower than the positron TCSs at 2-4 eV, otherwise elsewhere, electron TCSs for both C6H5Cl and C6F5Cl are greater than positron TCSs by a factor of 1-2 at energies up to 30 eV. In the comparative studies of TCSs for C6H5Cl with C6H6 and C6F5Cl and C6F6, the magnitude of TCSs is found to be in the order of the molecular size over all energy ranges, except positron TCSs for C6H5Cl and C6H6 below 600 eV. (C) 2003 American Institute of Physics.