  A natural gradual extension of the idea of Grand Unification is to attempt to
relate the gauge and Yukawa couplings; Gauge-Yukawa Unification (GYU). However,
within the framework of renormalizable field theories, there exists no
realistic symmetry that leads to a GYU. Here we propose an approach to GYU
which is based on the principle of the reduction of couplings and finiteness in
supersymmetric Grand Unified Theories. We elucidate how the observed top-bottom
mass hierarchy can be explained in terms of supersymmetric GYU by considering
an example of the $SU(5)$ Finite Unified Theory. It is expected that, when more
accurate measurements of the top and bottom quark masses are available, it will
be possible to discriminate among the various GYU models.
