Validated up-to-date codes and methods for fast reactor core physics analysis are of critical importance. This publication arises from a coordinated research programme on updated codes and methods to reduce the calculational uncertainties of the LMFR reactivity effects. It presents the results of the benchmark analyses of the hybrid BN-600 reactor core loaded with UOX and MOX fuel. It addresses the benchmark definitions and specifications used in each phase; briefly introduces the basic data, computer codes and methodologies applied by the various participants; refers to the results of an inter-comparison of phases 1, 2 and 3; and finally addresses the conclusions drawn from the benchmark studies.