The only time “DWORD PTR” is required is when (1) you're working with old assemblers, or (2) you're using a memory operand with an immediate: add eax, [4]

The only time “DWORD PTR” is required is when (1) you're working with old assemblers, or (2) you're using a memory operand with an immediate: add eax, [4] ; inferred add [eax], 4 ; ambiguous add DWORD [eax], 4 ; explicit A disassembler may output it when not necessary, however.