  Recent diffractive structure function measurements by the H1 and ZEUS
experiments at HERA are reviewed. Various data sets, obtained using
systematically different selection and reconstruction methods, are compared.
NLO DGLAP QCD fits are performed to the most precise H1 and ZEUS data and
diffractive parton densities are obtained in each case. Differences between the
Q^2 dependences of the H1 and ZEUS data are reflected as differences between
the diffractive gluon densities.
