> For the complete documentation index, see [llms.txt](https://docs.belugas.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.belugas.io/atokens/repay-borrow.md).

# Repay Borrow

The repay function transfers an asset into the protocol, reducing the user's borrow balance.

**BErc20**

```
function repayBorrow(uint repayAmount) returns (uint)
```

* `msg.sender`: The account which borrowed the asset, and shall repay the borrow.
* `repayAmount`: The amount of the underlying borrowed asset to be repaid. A value of -1 (i.e. 2 ^ 256 - 1) can be used to repay the full amount.
* `RETURN`: 0 on success, otherwise an [Error code](/atokens/error-codes.md)

Before repaying an asset, users must first [approve](https://eips.ethereum.org/EIPS/eip-20#approve) the bToken to access their token balance.

**CEther**

```
function repayBorrow() payable
```

* `msg.value` *\[payable]*: The amount of ether to be repaid, in wei.
* `msg.sender`: The account which borrowed the asset, and shall repay the borrow.
* `RETURN`: No return, reverts on error.

**Solidity**

```
CEther bToken = CEther(0x3FDB...);
require(bToken.repayBorrow.value(100)() == 0, "transfer approved?");
```

**Web3 1.0**

```javascript
const bToken = BErc20.at(0x3FDA...);
bToken.methods.repayBorrow(10000).send({from: ...});
```


---

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