Croup (also called laryngotracheobronchitis) is a disease which afflicts infants and young children, typically aged between 3 months and 5 years. It is characterized by a harsh 'barking' cough, inspiratory stridor and fever.

It is most often caused by parainfluenza virus, but other viral and bacterial infections can also cause it.

The word may also refer to the rump of a quadruped (see croupier).