Hello Alex,

thx. I am one step further!
The calling app is mfc. The dll non-mfc.
Now, I included
#define _CRTDBG_MAP_ALLOC
#include <stdlib.h>
#include <crtdbg.h>
in the header files of the dll.

This leads to the following:
1) when I call _CrtDumpMemoryLeaks() I get a dump.
But it says for every memory block that it is created in crtdbg.h (552), not the actual line of code that calls "new".
2) there is no automatic dump of the dll-leaks when the app ends.

Can you help?!

Thx
Ralf