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Regiment or the regimental system (Ukrainian: полк, romanized: polk, Ukrainian: полковий устрій, romanized: polkovyi ustrii) is a historical administrative, territorial, military and judicial unit of the country's subdivision of the Cossack Hetmanate and the Sloboda Ukraine in the 17th–18th centuries.[1]
System was expanded out of already existing system of the Registered Cossacks over Kyiv, Bratslav and Chernihiv Voivodeships in the Polish–Lithuanian Commonwealth.
Regiments were headed by the Cossack Colonel (Ukrainian: полковник, romanized: polkovnyk) who was a member of the Cossack Council of the Officers (Ukrainian: рада старшин, romanized: rada starshyn).
Regiment was the first level of the administrative and military division of the Cossack Hetmanate.
| Subdivisions of the Cossack Hetmanate | ||
|---|---|---|
| First | Regiment | Ukrainian: полк, romanized: polk, pl. Ukrainian: полки, romanized: polky |
| Second | Sotnia | Ukrainian: сотня, romanized: sotnia, pl. Ukrainian: сотні, romanized: sotni |
| Third | Kurin | Ukrainian: курінь, romanized: kurin, pl. Ukrainian: курені, romanized: kureni |
In 1649, when the Cossack Hetmanate was established by the Treaty of Zboriv and controlled both the right and left banks, it included 16 regiments. After the loss of the Right–Bank Ukraine, a number was reduced to 10 regiments.

| Regiment | Ukrainian | Coat of arms | Years of formation |
|---|---|---|---|
| Chyhyryn Regiment | Чигиринський | 1625–1678 | |
| Cherkasy Regiment | Черкаський | 1625–1686 | |
| Korsun Regiment | Корсунський | 1625–1712 | |
| Bila Tserkva Regiment | Білоцерківський | 1625–1712 | |
| Kaniv Regiment | Канівський | 1625–1712 | |
| Pereyaslav Regiment | Переяславський | 1625–1782 | |
| Kyiv Regiment | Київський | 1625–1782 | |
| Myrhorod Regiment | Миргородський | 1625–1782 | |
| Ovruch Regiment | Овруцький | 1648–? | |
| Irkliyiv Regiment | Іркліївський | 1648–1648 | |
| Sosnytsia Regiment | Сосницький | 1648–1648 | |
| Chornobyl Regiment | Чорнобильський | 1648–1649 | |
| Borzna Regiment | Борзнянський | 1648–1649 | |
| Zhyvotiv Regiment | Животівський | 1648–1649 | |
| Ichnya Regiment | Ічнянський | 1648–1649 | |
| Hadyach Regiment | Гадяцький | 1648–1649 | |
| Zviahel Regiment | Звягельський | 1648–1649 | |
| Ostropil Regiment | Остропільський | 1648–1649 | |
| Podillya Regiment | Подільський | 1648–1649 | |
| Lyubartiv Regiment | Любартівський | 1648–1649 | |
| Lysianka Regiment | Лисянський | 1648–1657 | |
| Bratslav Regiment | Брацлавський | 1648–1667 | |
| Vinnytsia Regiment | Вінницький | 1648–1667 | |
| Uman Regiment | Уманський | 1648–1675 | |
| Pavoloch Regiment | Паволоцький | 1648–1675 | |
| Poltava Regiment | Полтавський | 1648–1675 | |
| Lubny Regiment | Лубенський | 1648–1781 | |
| Nizhyn Regiment | Ніжинський | 1648–1782 | |
| Pryluky Regiment | Прилуцький | 1648–1782 | |
| Chernihiv Regiment | Чернігівський | 1648–1782 | |
| Kropyvna Regiment | Кропивнянський | 1649–1658 | |
| Chechelnyk Regiment | Чечельницький | 1650–1673 | |
| Novhorod Regiment | Новгородський | 1653–1654 | |
| Belarus Regiment | Білоруський | 1654–1659 | |
| Pinsk–Turiv Regiment | Пінсько-Турівський | 1654–1659 | |
| Starodub Regiment | Стародубський | 1654–1782 | |
| Kremenchuk Regiment | Кременчуцький | 1661–1666 | |
| Hlukhiv Regiment | Глухівський | 1663–1665 | |
| Zinkiv Regiment | Зіньківський | 1671–1782 | |
| Fastiv Regiment | Фастівський | 1684–1712 | |
| Bohuslav Regiment | Богуславський | 1685–1712 |