Progress of the research on microstructural evolution during radiation damage accompanied with collision cascades, particularly by neutrons, is summarized from the research papers published since 1992. The major part of irradiation was performed with JMTR (Japan Materials Testing Reactor), and comparisons were made with the result of D-T fusion neutron irradiation with RTNS-II (Rotating Target Neutron Source, LLNL). The subjects concerned are : (1) Correlation of high-energy particle irradiation by use of the recoil energy spectrum, (2) Cascade localization induced bias effect for void growth, (3) Influence of primary recoil energy spectrum on microstructural evolution, (4) Variation of the cascade localization induced bias effect with material parameters and irradiation conditions, (5) Fluctuation effect of point defect reaction on nucleation of interstitial clusters, (6) Binary collision calculation of subcascade structure and its correspondence to observed subcascade defects in 14 MeV neutron irradiated copper, (7) Detection of the role of free point defects from the variation of defect structures near permanent sinks, (8) Low dose fission neutron irradiation on P- and Ti-modified austenitic alloys with improved temperature control, (9) Role of free point defects in defect structure evolution during cascade damage, (10) Origin of unbalanced reaction of vacancies and interstitial during irradiation with cascades and influence on microstructural evolution, (11) Influence of details of reactor history on microstructural development, (12) Exposure time and recoil energy dependence of defect accumulation, (13) Development of controlled temperature-cycle irradiation technique in JMTR, (14) Microstructure evolution by neutron irradiation during cyclic temperature variation, (15) Role of solute atoms on microstructural evolution in neutron irradiated nickel, (16) Microstructural evolution in low dose neutron irradiated Fe-15Ni-15Cr alloy, and (17) Effect of cascade localization induced bias effect and fluctuation of point defect reactions on defect structure evolution near planar sinks
