Inspection of neutron-irradiation-generated degradation is a very important task. In ferromagnetic materials, such as nuclear reactor pressure vessel steel, the structural degradation is connected with a change of their magnetic properties. In this work the applicability of a novel magnetic nondestructive method (Magnetic Adaptive Testing, MAT), which is based on systematic measurement and evaluation of minor magnetic hysteresis loops, is shown for inspection of neutron irradiation embrittlement in nuclear reactor pressure vessel steel. Three series of samples, made of JRQ, 15H2MFA and 10ChMFT type steels were measured by MAT. The samples were irradiated by E>1 MeV energy neutrons with neutron fluence of 1.58×1019 - 1.19×10 20 n/cm2. Regular, monotonously increasing correlation was found between the optimally chosen MAT degradation functions and the neutron fluence, in all three types of the materials. Shift of the ductile-brittle transition temperature, Δ DBTT, independently determined as a function of neutron fluence for the 15H2MFA material, was also employed. A sensitive, linear correlation was found between the ? DBTT and values of the MAT degradation functions. Based on these results, MAT is considered to be a promising complimentary tool. It can serve in future, perhaps, even for replacement of the destructive tests within the surveillance programs, which are presently used for inspection of neutron irradiation generated embrittlement of nuclear reactor pressure vessel steel.