We present results for the interaction of two kaons at maximal isospin. The
calculation is based on 2+1+1 flavour gauge configurations generated by the ETM Collaboration (ETMC)
featuring pion masses ranging from about 230 MeV to 450 MeV at three values of the
lattice spacing.
The elastic scattering length a^{I=1}_0 is calculated at several values of the bare strange quark and
light quark masses. We find MKa0 = -0.397(11)(+0 -8) as the result of a chiral and continuum
extrapolation to the physical point. This number is compared to other lattice
results.
