  Recently Kordas (1995, Class. Quantum Grav. 12 2037) and Meinel and
Neugebauer (1995, Class. Quantum Grav. 12 2045) studied the conditions for
reflection symmetry in stationary axisymmetric space--times in vacuum. They
found that a solution to the Einstein field equations is reflectionally
symmetric if their Ernst's potential ${\cal E}(\rho=0,z)= e(z)$ on a portion of
the positive z-axis extending to infinity satisfies the condition
$e_{+}(z){e}_{+}^{*}(-z)=1$. In this note, we formulate an analogous conditions
for two complex Ernst potentials in electrovacuum. We also present the special
case of rational axis potentials.
