Route 155 is a Connecticut state highway running entirely within the city of Middletown.

The entire length of Route 155 is known as Randolph Road.

Route 155 is a minor arterial road and carries traffic volumes of about 10,100 per day.

The eastern terminus has since been shifted from Saybrook Road to the current location, when Route 9 was moved to its expressway alignment in 1967.

The entire route is in Middletown, Middlesex County.