  We discuss the role of D0-branes as instantons in the construction of SU(N)
Super Yang-Mills and Super QCD theories in four space-time dimensions with D4-,
D6- and NS-branes.
  [To appear in the proceedings of the conference "Quantum Aspects of Gauge
Theories, Supersymmetry and Unification", held at Neuchatel University,
Neuchatel, Switzerland, 18--23 September 1997.]
