We report preliminar results on the measurement of the isolated
prompt photon cross section as a function of photon transverse
momentum  $p^\gamma_T$ at the Tevatron using 3 fb${}^{-1}$ of data
collected by the CDF experiment in Run II. The measurements are
performed for photons with $p^\gamma_T$  above 30~GeV/$c$ and
rapidity in the region $|\eta^{\gamma}| < 1$.  The measurements
are compared to next-to-leading order perturbative QCD predictions.