Jose G. Arevalo, 83, was last seen Thursday near 19th Street and Scoville Avenue, according to an endangered persons alert.
He is 5-foot-7, 150 pounds and suffers from Alzheimer's.
Arevalo, who is Spanish speaking only, also responds to the names Guadalupe, Pepe and Lupe.
He was last seen wearing a green-colored flannel shirt, a Cubs baseball hat, blue jeans with flannel lining and black shoes.
Arevalo previously lived in Chicago's Little Village neighborhood.
Anyone with information on Arevalo's whereabouts is asked to contact Berwyn police at (708) 795-5600.