A cute video has emerged capturing a boy's disappointed reaction as he learns he is having a baby sister.

The footage, shot on July 7 in Niagara Falls, NY, USA, shows the boy and his sister walking into the hospital where their mother has given birth.

As their father asks them whether they think it's a boy or a girl, the daughter guesses right when the son hopes the new baby will be a boy.

When their father breaks the news, the boy holds his hands to his face and starts sobbing.