| Singular | Plural | |
|---|---|---|
| Nominativ | efficacia | efficaciae |
| Genitiv | efficaciae, efficaciai | efficaciarum, efficacium |
| Dativ | efficaciae, efficaciai | efficaciis, efficaciabus |
| Akkusativ | efficaciam | efficacias |
| Ablativ | efficacia, efficaciad | efficaciis, efficaciabus |
| Vokativ | efficacia | efficaciae |