| Nominative | ostrov |
| Genitive | ostrova |
| Dative | ostrovu |
| Accusative | ostrov |
| Vocative | ostrove |
| Locative | ostrově |
| Instrumental | ostrovem |
| Nominative | ostrovy |
| Genitive | ostrovů |
| Dative | ostrovům |
| Accusative | ostrovy |
| Vocative | ostrovy |
| Locative | ostrovech |
| Instrumental | ostrovy |