The stabbing was reported at about 1:30 a.m. near Mission and 24th streets.
The victim was walking when a suspect approached and stabbed him twice in the shoulder and bicep, according to police.
The suspect then told the victim to run away before fleeing on foot, police said.
The victim was taken to San Francisco General Hospital to be treated for his injuries, which are not considered life-threatening.
The suspect, a man in his 20s, had not been found as of this morning. Anyone with information about the stabbing is encouraged to call the Police Department's anonymous tip line at (415) 575-4444 or send a tip by text message to TIP411.