Police received a call at 5:46 a.m. from someone who said they saw a body on the side of the road on Glenwood Avenue near Middlefield Road, Atherton police Lt. Joe Wade said.
Officers responded and found that a man believed to be between 25 and 40 years old had been struck and killed by a vehicle, Wade said. The man's name was not immediately being released.
The vehicle that struck the pedestrian drove away and has not been found, Wade said.
He said anyone who may have witnessed the hit-and-run or who has information about the case is asked to call Atherton police at (650) 688-6500.
Middlefield Road, a main thoroughfare in Atherton, was expected to be closed between Oak Grove and Encinal avenues until later this morning while police investigate the death, Wade said.