The Republic of the Marshall Islands requested a natural and cultural biodiversity survey of 6 northern atolls (Bok-ak, Pikaar, Toke, Wotto, Roiidik, Adkup) and one reef island (Jenq) which was accomplished over 17 days in September 1988. This report covers the results of the survey of the reefs and corals during the expedition. Ninety-five marine sites were snorkeled and the shorelines of all island were surveyed during the expedition. A total of 168 species and 55 genera and subgenera of stony corals were reported including several new species and one new genus recorded (Polyphyllia) for the Marshalls.Bok-ak Atoll, the northernmost atoll, supports large giant clam populations, a completely native flora, and the largest seabird populations in the Marshalls. Pikaar Atoll also supports large giant clam populations and the largest sea turtle nesting populations in the Marshalls. Both Bok-ak and Pikaar are isolated from other atolls and have shallow lagoons elevated slightly above sea level due to their geomorphological configuration. Toke Atoll is located about 10 km from inhabited Utrok Atoll, and supports healthy coral reef habitats and giant clams. Jemq Island supports large seabird populations and is the second most important sea turtle nesting site in the Marshalls. Boat access to Jemy, Pikaar and Bok-ak is hazardous due to wave exposure or strong currents. Rofidik Atoll supports healthy coral reefs, blue coral habitats, pink foraminiferan sand beaches, and large coconut crab populations. Adkup supports abundant seabird populations, sea turtle nesting populations, and healthy coral reefs. Inhabited Wotto also supports healthy coral, coconut crab, sea turtle and giant clam habitats and has beautiful beach, reef and lagoon habitats.On the basis of the surveys, Bok-ak, Pikaar and Jerng are recommended for designation as limited entry ecological preserves. Toke is recommended as a national park accessible to both tourists and residents. Limited sport diving and beach-going is also suitable for Roiidik and Adkup. Assistance should be provided to the people of Wotto Atoll to fulfill their desire for small scale adventure tourism.Program on Environment, East-West Center