| Nominativ | fideicommissarius, fideicommissaria, fideicommissarium | fideicommissaria, fideicommissarii, fideicommissariae |
| Genitiv | fideicommissarii, fideicommissarii, fideicommissariae | fideicommissariorum, fideicommissariorum, fideicommissariarum |
| Dativ | fideicommissario, fideicommissario, fideicommissariae | fideicommissariis |
| Akkusativ | fideicommissarium, fideicommissarium, fideicommissariam | fideicommissaria, fideicommissarios, fideicommissarias |
| Ablativ | fideicommissario, fideicommissario, fideicommissaria | fideicommissariis |
| Vokativ | fideicommissarie, fideicommissaria, fideicommissarium | fideicommissaria, fideicommissarii, fideicommissariae |
