Hipolito Canseco, 53, was last seen at about 9 p.m. and lives at 1315 Vine St.
His family said Canseco suffered a head injury when he was 10 years old and as a result, his mental capacity is that of a 10-year-old. He can only provide his name and only speaks Spanish, police said.
Canseco also has a history of seizures.
He is described as a Hispanic man, standing 5 feet 2 inches tall, weighing 130 pounds, with salt-and-pepper hair, a black mustache and a medium build, police said.
He was last seen wearing a white T-shirt, dark blue sweatpants and sandals.
Anyone with information about Canseco's whereabouts is asked to call San Jose police at (408) 277-4786 or dial 911.