Police responded to a report of an assault near the corner of Park Avenue and Poplar Street at 3:05 a.m.
Officers found the woman there and determined she had been sexually assaulted, police said.
A suspect had been seen running northwest away from the scene, but no arrests have been made in the case.
Anyone with information about this assault has been asked to call Santa Clara police at (408) 615-4813.
ABC7 News contributed to this report.