| Role | Voice Part | Classification |
|---|---|---|
| Medea | Soprano | L |
| Jason | Tenor | L |
| Glauce (Dirce) | Soprano | F |
| Creon | Bass | F |
| Neris | Mezzo-Soprano | S |
| First Maidservant (Ancella) | Soprano | B |
| Second Maidservant (Ancella) | Mezzo-Soprano | B |
| Captain of the Guard | Bass | B |
| 2 Children of Medea | Silent | |
| Minimum Chorus: 24 | ||
| Divisi: SATB |