The production of exclusive γγ→μ+μ- events in proton?proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC, using data corresponding to an integrated luminosity of 3.2 fb -1 . The measurement is performed for a dimuon invariant mass of 12GeV<mμ+μ-<70GeV . The integrated cross-section is determined within a fiducial acceptance region of the ATLAS detector and differential cross-sections are measured as a function of the dimuon invariant mass. The results are compared to theoretical predictions both with and without corrections for absorptive