Authorities said the suspect entered the Crescent State Bank on Creedmoor Road in Raleigh around 9:30 a.m. Thursday.
They said he passed a note to a bank teller and fled after the teller complied with the note's demands. The contents of the letter are unknown.
The suspect is described as an African American man standing 5' 9" tall and weighing about 215 pounds.
He was wearing a white button-up shirt, along with black plants, shoes and baseball cap at the time of the robbery. He also wore sunglasses with plastic frames.
The suspect had what appeared to be a beard or goatee based on an image from surveillance video.
He was last seen fleeing on foot, going east on Sawmill Road.
Anyone who believes they might recognize the suspect is asked to call Raleigh CrimeStoppers at (919) 834-HELP.