.386
.model flat, stdcall 
option casemap:none 

include windows.inc
include kernel32.inc  
include user32.inc
includelib kernel32.lib  
includelib user32.lib

.data 
MsgBoxCaption  db "Simple MessageBox Program",0 
MsgBoxText     db "Hello World!",0 

.code 
start: 
invoke MessageBox, NULL, addr MsgBoxText, addr MsgBoxCaption, MB_OK  
invoke ExitProcess,0
end start