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Several Monte Carlo systems were benchmarked against published measurements of bremsstrahlung yield from thick targets for beams. The quantity measured was photon fluence at per unit energy per incident electron (spectra), and total photon fluence, integrated over energy, per incident electron (photon yield). Results were reported at on the beam axis for Al and Pb targets and at at angles out to 90° for Be, Al, and Pb targets. Beam energy was revised with improved accuracy of 0.5% using an improved energy calibration of the accelerator. Recently released versions of the Monte Carlo systems EGSNRC , GEANT4 , and PENELOPE were benchmarked against the published measurements using the revised beam energies. Monte Carlo simulation was capable of calculation of photon yield in the experimental geometry to 5% out to 30°, 10% at wider angles, and photon spectra to 10% at intermediate photon energies, 15% at lower energies. Accuracy of measured photon yield from 0 to 30° was 5%, , increasing to 7% for the larger angles. EGSNRC and PENELOPE results were within of the measured photon yield at all beam energies and angles, GEANT4 within Photon yield at nonzero angles for angles covering conventional field sizes used in radiotherapy (out to 10°), measured with an accuracy of 3%, was calculated within of measurement for EGSNRC , for PENELOPE and GEANT4 . Calculated spectra closely matched measurement at photon energies over . Photon spectra near were underestimated by as much as 10% by all three codes. The photon spectra below for the Be and Al targets and small angles were overestimated by up to 15% when using EGSNRC and PENELOPE , 20% with GEANT4 . EGSNRC results with the NIST option for the bremsstrahlung cross section were preferred over the alternative cross section available in EGSNRC and over EGS4 . GEANT4 results calculated with the “low energy” physics list were more accurate than those calculated with the “standard” physics list.