"This is a preventive measure to protect visitors and objects, especially during crowded conditions," The Smithsonian, the largest research and museum group in the world, said in a statement.
The selfie stick allows you a longer reach when using a smartphone or camera to take a picture of yourself.
"We encourage museum visitors to take selfies and share their experiences and leave the selfie sticks in their bags," the Smithsonian said.
The new rule is the first change in years to the Smithsonian's rules.
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"I don't think 10 years ago that you could have predicted there would even be such a thing, let alone that it would be so popular."
The Smithsonian consists of 19 museums and galleries in the US capital, the National Zoological Park and nine research centres. It had more than 28 million visits last year.
The Smithsonian is not alone in saying no to the new selfie accessory.
Similar restrictions on the tourist item have been enforced at museums and galleries in the US in recent months including New York's Metropolitan Museum of Art and Modern Museum of Art, the Getty Center in Los Angeles and the Cleveland Museum of Art.