# GetExistingSystemState<T>()

> Return the system state for an existing instance of a system of type T in this World.

## Definition

* **Type:** Method
* **Namespace:** [Unity.Entities](/engine/7000.0/script-reference/unity/entities.md)
* **Assembly:** UnityEngine.EntitiesModule

```csharp
public ref SystemState GetExistingSystemState<T>()
```

### Returns

| Type                                                                         | Description                                                                                                      |
| ---------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------- |
| [SystemState](/engine/7000.0/script-reference/unity/entities/systemstate.md) | The system state for the existing instance of system type `T` in this World. If no such instance exists, throws. |