Critical experiments that used high-concentration mixed-oxide (MOX) fuels in boiling water reactor lattice configurations and that were performed in the VENUS International Program are analyzed with CASMO-4 (C-4) /SIMULATE-3 (S-3). Both heterogeneous full-core transport calculations by C-4 and nodal diffusion calculations by S-3 with single-bundle CASMO-4 constants are performed, and the obtained results, such as eigenvalues and pin power distributions, are compared against the measured results. The agreement between the calculations and the measurements is quite satisfactory, and a good predictive capability of C-4 and S-3 for MOX fuels is verified.