  The tridimensional configuration and the twist density of helical rods with
varying cross section radius are studied within the framework of the Kirchhoff
rod model. It is shown that the twist density increases when the cross section
radius decreases. Some tridimensional configurations of helix-like rods are
displayed showing the effects of the nonhomogeneity considered here. Since the
helix-like solutions of the nonhomogeneous rods do not present constant
curvature and torsion a set of differential equations for these quantities is
presented. We discuss the results and possible consequences.
