The (1; 0) supersymmetry in six dimensions admits a tensor multiplet w
hich contains a second-rank antisymmetric tensor field with a self-dua
l field strength and a dilaton. We describe the fully supersymmetric c
oupling of this multiplet to a Yang-Mills multiplet, in the absence of
supergravity. The self-duality equation for the tensor field involves
a Chern-Simons modified field strength, the gauge fermions and an arb
itrary dimensionful parameter.