Retkowy was formerly part of the German Empire. In the German Empire, the place was called Rettkau (Ostpr.).
The place is now called Retkowo and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Rettkowen | German Empire | Neidenburg | 1938 |
| Rettkau (Ostpr.) | German Empire | Neidenburg | 1939 |
| Retkowy | Under Polish administration | Nidzica | 1945 |
| Retkowo | Poland | Olsztyn | 1992 |