This weekend plenty of people will be out trick or treating or hitting the town for a spooky night out.
You might see traditional orange pumpkins outside of people's houses to mark the occasion.
And you might also see some blue ones too.
Blue pumpkins are used to represent autism, and to express that they may have certain needs.
The idea was started by a mother in America who took to Facebook to highlight her decision to use a blue bucket, the Manchester Evening News reports.
She said: "If you see someone who appears to be an adult dressed up to trick or treat this year carrying this blue bucket, he’s our son!
"His name is BJ & he is autistic. While he has the body of a 21 year old, he loves Halloween.
"Please help us keep his spirit alive & happy. So when you see the blue bucket share a piece of candy. Spread awareness! These precious people are not “too big” to trick or treat."
The post from October 26 has since been shared more than 27,000 times.
Teal pumpkins may also be visible due to another campaign which also started in America in 2016.
The Teal Pumpkin Project is an awareness campaign from Food Allergy Research and Education (FARE) and aims to make sure children with food allergies or other dietary restrictions can also enjoy trick or treating.
The pumpkin, if put outside your home, is a clear sign to parents and children that there are non-food treats available.
