Maryland Route 408 (MD 408), known locally as Mt Zion - Marlboro Road, is an east–west highway in Anne Arundel County, Maryland. This route heads east from its interchange with Stephanie Roper Highway to its terminus with Solomons Island Road and Bayard Rd at the Lothian Roundabout. It is a former designation of Maryland Route 4.

MD 408 begins at a three-quarter diamond interchange with MD 4 (Stephanie Roper Highway) just west of Waysons Corner. The roadway continues south from the interchange as MD 980A, a service road that curves east and parallels southbound MD 4 toward Bristol. The missing ramp in the diamond interchange, the movement from northbound MD 4 to MD 408, is made via MD 794 (Southern Maryland Boulevard) at the oblique intersection that forms Waysons Corner. MD 408 continues east as a two-lane road through a mix of forest and farmland. The highway veers northeast beyond its intersection with MD 259 (Greenock Road) and passes the historic home Quarter Place. MD 408 reaches its eastern terminus in Lothian at a four-way roundabout from which MD 2 (Solomons Island Road) heads northeast toward Annapolis and southeast in the direction of Prince Frederick, and MD 422 heads northwest along Bayard Road.

The entire route is in Anne Arundel County.