Yes, U.S. citizens age 21 or older can file a petition for their brother or sister to immigrate.

The process starts by filing Form I-130 (Petition for Alien Relative) with USCIS, proving the sibling relationship.

If you're outside the U.S., you'll apply for your green card through consular processing when your priority date becomes current.

 If you're already in the U.S., you may need to leave and apply from abroad unless you qualify to adjust status lawfully.