  The photon-proton total cross section has been measured in the process e+ p
-> e+ gamma p -> e+ X with the ZEUS detector at HERA. Events were collected
with photon virtuality Q^2 < 0.02 GeV^2 and average gamma-p center-of-mass
energy W_{gamma p} = 209 GeV in a dedicated run, designed to control systematic
effects, with an integrated luminosity of 49 nb^{-1}. The measured total cross
section is sigma_{tot}^{gamma p} = 174 +- 1 (stat.) +- 13 (syst.) microbarns.
The energy dependence of the cross section is compatible with parameterizations
of high-energy p-p and p-pbar data.
