Puerto Rico Highway 181 (PR-181), also known as Expreso Trujillo Alto (Trujillo Alto Expressway),[3] is a road in Puerto Rico connecting the municipality of San Juan on the northeastern coastal plain with Patillas on the southeastern coastal plain.

Beginning in the Rio Piedras district of barrio Oriente in San Juan at Jesus de Piñero Avenue (PR-17), it runs through Trujillo Alto, Gurabo and San Lorenzo on the Caguas Valley, and western Yabucoa and eastern Patillas on the Sierra de Cayey, before ending in the Patillas Pueblo downtown area on the southeastern coastal plain of Puerto Rico.

PR-181 is a four-lane highway from San Juan through the Trujillo Alto Pueblo downtown area, and completely rural on the way to Patillas with the exception of a small tract in Gurabo where it intersects PR-30.

In Trujillo Alto, near Gurabo, it turns into a rural road with very narrow lanes per direction and hard curves, making it dangerous and requiring low speed limits.

In Gurabo, it becomes divided in about 1 kilometer as it intersects Puerto Rico Highway 30, and then quickly turns rural.