A method of protecting a DRAM memory device from the row hammer effect, the memory device comprising a plurality of banks composed of memory rows, may be implemented by at least one logic prevention device configured to respectively associate contiguous sections of rows of a bank with sub-banks. The prevention logic is also configured to execute a preventive refresh cycle of the sub-banks that is entirely executed before the number of rows activated in a sub-bank exceed a critical hammer value. A DRAM memory device, a buffer circuit or a controller of such a memory may comprise the logic for preventing the row hammer effect.