An amusing video has emerged of a young boy reacting badly to news he is about to get a younger sister.

In the footage, captured by the boy's parents at their 'gender reveal' party in American Fork, Utah, US late last month, the parents reveal the news that their third child is going to be a girl by releasing pink balloons from a box.

While assembled partygoers cheer, the couple’s son bursts into tears, apparently devastated by the news.

"We were excited to reveal the gender of our third baby to our family and friends...unfortunately our little guy was quite disappointed with the news!" his parents later wrote online.

An amusing video has emerged of a young boy reacting badly to news he is about to get a younger sister.

In the footage, captured by the boy's parents at their 'gender reveal' party in American Fork, Utah, US late last month, the parents reveal the news that their third child is going to be a girl by releasing pink balloons from a box.

While assembled partygoers cheer, the couple’s son bursts into tears, apparently devastated by the news.

"We were excited to reveal the gender of our third baby to our family and friends...unfortunately our little guy was quite disappointed with the news!" his parents later wrote online.