  The precision measurements of the strong coupling constant, alphas, and its
energy-scale dependence carried out at HERA by the H1 and ZEUS Collaborations
are reviewed. An average value of alphas(Mz) = 0.1186 +- 0.0011 (exp.) +-
0.0050 (th.) is obtained from these measurements. The combined HERA
determinations of the energy-scale dependence of alphas clearly show the
running of alphas from jet data alone and are in agreement with the running of
the coupling as predicted by QCD.
