Patrol Boat, Riverine, or PBR, is the United States Navy designation for a small rigid-hulled patrol boat used in the Vietnam War from March 1966 until 1975. They were deployed in a force that grew to 250 boats, the most common craft in the River Patrol Force, Task Force 116, and were used to stop and search river traffic in areas such as the Mekong Delta, the Rung Sat Special Zone, the Saigon River and in I Corps, in the area assigned to Task Force Clearwater, in an attempt to disrupt weapons shipments. In this role, they frequently became involved in firefights with enemy soldiers on boats and on the shore, were used to insert and extract Navy SEAL teams, and were employed by the United States Army's 458th Transportation Company, known as the 458th Sea Tigers.

A patrol boat is a relatively small naval vessel generally designed for coastal defence, border security, or law enforcement. There are many designs for patrol boats, and they generally range in size. They may be operated by a nation's navy, coast guard, police, or customs, and may be intended for marine, estuarine, or river environments.