The composition of biofouling communities on three offshore platforms in the Gulf of Mexico was examined. A platform in South Timbalier block 54 lay in 22 m of water 40 km from shore. A platform in Grand Isle block 94 lay in 60 m of water 86 km offshore. A platform in Green Canyon lease block 18 lay in 219 m at 150 km offshore near the edge of the continental shelf. The three platforms had been the site of previous fisheries-related investigations and offered an offshore gradient. Research operations were carried out from the platforms with Exxon and Mobil corporations hosting and providing logistical support. Field sampling was initiated in November 1995, and completed September 1997.