State Highway 323 or SH 323 is a Texas state highway running from Overton southeast to Henderson. The route was designated by 1939.

SH 323 begins at a junction with SH 135 in Overton. It heads southeast from this junction to an intersection with FM 838. The highway continues to the southeast to an intersection with SH 42. Heading towards the southeast, the highway continues to a junction with Loop 571. The highway continues to the southeast to an intersection with FM 2276. SH 323 reaches its eastern terminus at SH 64 in Henderson.