South Carolina Highway 903 (SC 903) is a 27.090-mile (43.597 km) primary state highway in the U.S. state of South Carolina.

It connects Lancaster to Darlington, Florence, and the Grand Strand.

SC 903 is a two-lane rural highway, from Catarrh to Lancaster.

Control cities listed southbound include Myrtle Beach.

[5][6] In 1949, SC 903 was extended north to its current northern terminus in Lancaster, replacing an old alignment of SC 9.