The 1991 USC Trojans football team represented the University of Southern California (USC) in the 1991 NCAA Division I-A football season. In their fifth year under head coach Larry Smith, the Trojans compiled a 3–8 record (2–6 against conference opponents), finished in eighth place in the Pacific-10 Conference (Pac-10), and were outscored by their opponents by a combined total of 276 to 229.