I thought it was clear that I ment address space when I wrote of "address start" (base address) and "address end". I know that it's called Address Space but I think the address space MUST have a beginning (I think this is the BASE ADDRESS of a process, which I already figured out how to get it) and I also think it should have an END because I don't think a process uses all of the momory in a system. Ok what I want to know is how to get the "End-Address" of the ADRESS SPACE. By the way I'm using Win9x. Thanks for your reply Tommy