Maryland Route 545 (MD 545) is a state highway in the U.S. state of Maryland. Known for most of its length as Blue Ball Road, the state highway runs 5.92 miles (9.53 km) from MD 213 in Elkton north to Kirk Road and Warburton Road at Pleasant Hill in central Cecil County. MD 545 was constructed to Little Elk Creek near Childs in the early 1930s and extended to Pleasant Hill in the late 1940s.

MD 545 begins at MD 213 (Bridge Street) on the west side of Elkton. The state highway heads west as Elkton Boulevard, a two-lane road through an industrial area. At Blue Ball Road, MD 545 turns northwest onto Blue Ball Road and intersects MD 279 (Elkton Road). The state highway's surroundings transition to a mix of farmland and forest after leaving the town of Elkton and passing Dogwood Road. MD 545 crosses Little Elk Creek immediately after passing under Interstate 95. The state highway has a narrow, curved passage under CSX's Philadelphia Subdivision as it enters the village of Childs. MD 545 has a four-way stop at Leeds Road and passes scattered residences in a forested area before reaching its northern terminus at an intersection with Kirk Road and Warburton Road in the hamlet of Pleasant Hill. Blue Ball Road continues northwest as a county highway.

MD 545 was paved from Easton Boulevard to Little Elk Creek near Childs in 1933. The bridge over Little Elk Creek was completed in 1932. MD 545 was extended to Pleasant Hill in 1949. In January 2010, the Maryland State Highway Administration put the 1932 pony truss bridge MD 545 uses to cross Little Elk Creek up for sale to any buyer willing to preserve the bridge at a new location. No interested party was found so the old bridge was demolished in June and July of 2011. The new bridge opened in November 2011.

The entire route is in Cecil County.