  We present and discuss a short and simple derivation of orbital epicyclic
frequencies for circular geodesic orbits in stationary and axially symmetric
spacetimes. Such spacetimes include as special cases analytically known black
hole Kerr and Schwarzschild spacetimes, as well as the analytic Hartle-Thorne
spacetime and all numerically constructed spacetimes relevant for rotating
neutron stars. Our derivation follows directly from energy and angular momentum
conservation and it uses the concept of the effective potential. It has never
been published, except for a few special cases, but it has already become a
part of the common knowledge in the field.
