The robbery was reported at 1:42 a.m. near 17th and Shotwell streets.
The 51-year-old victim was approached from behind by a man who punched her in the head, causing her to fall to the ground, according to police.
The woman and the suspect struggled over her purse before the man overpowered her, taking cash from the purse and a bracelet off of her wrist, police said.
The suspect, described as a man in his mid 20s, fled and had not been found as of this morning, police said.
The victim was taken to San Francisco General Hospital to be treated for swelling to her head as well as a bruised knee and arm. The injuries are not considered life-threatening, according to police.
Anyone with information about the case is asked to call the Police Department's anonymous tip line at (415) 575-4444 or to send a tip by text message to TIP411 with "SFPD" in the message.