How do you say In memory of my father in Polish?

The most straightforward translation of "In memory of my father" in Polish is:

W pamięci mojego ojca

However, depending on the context (e.g., inscription on a tombstone, dedication in a book), you might also use:

* Pamięci mojego ojca (Memory of my father) - This is shorter and more commonly used on memorials.

* Ku pamięci mojego ojca (To the memory of my father) - This is a more formal and slightly more poetic option.

The choice depends on the specific situation and desired tone. "W pamięci mojego ojca" is a safe and generally applicable option.