Kobylaki-Pietrusy was formerly part of the German Empire. In the German Empire, the place was called Kobylaki Pietrusy.
The place is now called Kobylaki-Pietrusy and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Kobylaki Pietrusy | Russian Empire | Prasnyš | 1914 |
| Kobylaki-Pietrusy | Poland | Przasnysz | 1919 |
| Kobylaki Pietrusy | German Empire | Praschnitz | 1939 |
| Kobylaki-Pietrusy | Poland | Przasnysz | 1945 |
| Kobylaki-Pietrusy | Poland | Ostrołęka | 1992 |