| Family | Genus | Species |
|---|---|---|
| Americobdellidae | 1 | 1 |
| Cylicobdellidae | 1 | 4 |
| Erpobdellidae | 6 | 219 |
| Gastrostomobdellidae | 1 | 3 |
| Haemadipsidae | 8 | 490 |
| Haemopidae | 3 | 23 |
| Hirudinidae | 15 | 68 |
| Orobdellidae | 1 | 26 |
| Ozobranchidae | 2 | 4 |
| Piscicolidae | 40 | 115 |
| Salifidae | 4 | 21 |
| Semiscolecidae | 2 | 6 |
| Xerobdellidae | 3 | 7 |