The "IAEA PWR benchmark problem" was intended to draw some conclusions about the accuracy of the different neutronic calculation codes used in the routine deterministic reactor calculation. The objective of this paper is to test the MCNP code against previously obtained solutions to provide new reference solutions to the IAEA benchmark with Monte Carlo method. The effective multiplication factor, radial and axial assembly power distributions and zone average group flux were calculated using Monte Carlo code (MCNP). The MCNP results are compared with the results of deterministic solutions in two and three dimensions. Good estimates of effective multiplication factor values and power distributionvalues in two and three dimensions were showed. To assess the MCNP results, the collective percent error measures were investigated. The results of AVG, MRE and RMS error measures were less than 1 % error. So all results presented here are considered an accurate reference solution and can using as Monte Carlo reference for IAEA PWR benchmark problem.