Method, system and product for direct access to de-duplicated data units in memory-based file systems. The method comprising: updating a page entry in a page table of a process to include a direct access pointer to a de-duplicated data unit retained by the memory-based file system, wherein the page entry is set to be write protected; detecting a page fault occurring due to the process performing a store instruction to the de-duplicated data unit; and in response to said detecting: allocating a new data unit; copying content of the de-duplicated data unit to the new data unit; and replacing the direct access pointer to the de-duplicated data unit with a direct access pointer to the new data unit.