# Redeem Underlying

The redeem underlying function converts aTokens into a specified quantity of the underlying asset, and returns them to the user. The amount of aTokens redeemed is equal to the quantity of underlying tokens received, divided by the current [Exchange Rate](https://docs.aquarius.loan/atokens/exchange-rate). The amount redeemed must be less than the user's [Account Liquidity](https://github.com/aquariusloan/aquarius-docs/tree/294e07fcebce7997c93709b5b9f8bbdb7e8271af/atokens/comptroller/get-account-liquidity.md) and the market's available liquidity.

**AErc20 / CEther**

```
function redeemUnderlying(uint redeemAmount) returns (uint)
```

* `msg.sender`: The account to which redeemed funds shall be transferred.
* `redeemAmount`: The amount of underlying to be redeemed.
* `RETURN`: 0 on success, otherwise an [Error code](https://docs.aquarius.loan/atokens/error-codes)

**Solidity**

```
CEther aToken = CEther(0x3FDB...);
require(aToken.redeemUnderlying(50) == 0, "something went wrong");
```

**Web3 1.0**

```javascript
const aToken = AErc20.at(0x3FDA...);
aToken.methods.redeemUnderlying(10).send({from: ...});
```