We calculate (g-2)/2 of the muon, by improving the determination of the hadronic vacuum polarisation contribution, a_mu^{had,LO}, and its uncertainties. The different e+e- data sets for each exclusive (and the inclusive) channel are combined in order to obtain the optimum estimate of the cross sections and their uncertainties. QCD sum rules are evaluated in order to resolve an apparent discrepancy between the inclusive data and the sum of the exclusive channels. We conclude a_mu^{had,LO}=(683.1 +- 5.9_{exp} +- 2.0_{rad}) 10^{-10} which, when combined with the other contributions to (g-2)/2, is about 3 sigma below the present world average measurement.