MD 242 connects the communities of Morganza, Clements, Bushwood, Avenue, and Coltons Point in western St. Mary's County.

MD 242 heads northwest as a two-lane undivided road through a mix of farmland and forest and scattered residences along the parallel St. Patrick's Creek.

The state highway veers northeast and intersects MD 238 (Maddox Road) in the hamlet of Milestown before crossing Tomakokin Creek.

The state highway crosses Dynard Run and parallels St. Clements Creek before arriving in the community of Clements, where the highway comes to a roundabout with MD 234 (Budds Creek Road), which connects Leonardtown to the east with U.S. Route 301 and the Governor Harry W. Nice Memorial Bridge to the west.

The state highway heads northeast through farmland, crossing Locust Run before passing west of Chopticon High School.