At this point, DE 15 turns northeast to join DE 299 on four-lane divided Middletown Warwick Road, entering commercial areas in the town of Middletown. At an intersection, the two routes split, with DE 15 heading northwest on Bunker Hill Road, DE 299 turning east onto West Main Street, and Middletown Warwick Road continuing north. Past DE 299, DE 15 is briefly a four-lane divided highway before it becomes a two-lane divided road, running through areas of homes and businesses and becoming undivided. The roadway passes over the US 301 toll road without an interchange before heading northeast of Appoquinimink High School. At a roundabout, the route turns north onto Choptank Road and leaves Middletown, heading through agricultural areas with some woods and residential development and coming to a roundabout with Churchtown Road. DE 15 intersects the eastern terminus of DE 286 at a roundabout and continues northeast along Bethel Church Road, ending at an intersection with DE 71/DE 896 in Summit Bridge, just south of the Summit Bridge over the Chesapeake & Delaware Canal.