State Highway 338, abbreviated SH 338, is a 6.722-mile (10.818 km) state highway in the U.S. state of Texas. The highway begins at a junction with U.S. Highway 259 (US 259) in Rocky Branch and heads north to a junction with State Highway 77 (SH 77) in Naples.

SH 338 was designated in 1940 to serve as a route between Rocky Branch and Naples.

SH 338 begins at a junction with US 259 in Rocky Branch. It heads north from this junction to an intersection with FM 161. SH 338 reaches its northern terminus at SH 77 in Naples.