>I run an external program using ShellExecute that convert some data that I have to process, my problem is how instruct my program to wait until the external program will finish. I can not modify the external program.

Ciao Luigi:

You can do it with WSH:

#define SW_SHOW_NORMAL 1
#define SW_SHOW_MINIMIZED 2
#define SW_SHOW_MAXIMIZED 3
oShell = createobject("WScript.Shell")
oShell.Run("notepad.exe",SW_SHOW_NORMAL,.T.)

or

ShellExecute (Windows API): see message#966019