  The effect coming from imaginary parts of effective couplings in the $e^+
e^-$ asymmetries is investigated. It is shown that for the present level of
experimental accuracy, in some asymmetries the imaginary parts of the effective
couplings cannot be neglected and moreover that the use of different
prescriptions on how to handle them in quoting just real effective couplings
from the data may produce sizable differences. A definition of the real
effective couplings specifying how to handle the imaginary parts is advocated.
