As more and more structural materials are used in marine and offshore service, studies on the effects of fouling organisms on corrosion and cathodic protection phenomena have gained renewed importance. This communication describes the common fouling organisms of Tuticorin harbour and their possible association in corrosion processes. Earlier studies on fouling in Tuticorin waters are restricted to panel data from a creek1 and to the occurrence of sessile organisms on pearl oysters in harbour waters2• The study area is located in Tuticorin harbour (lat. 8° 47' lO''N; long. 78°9'60''E) at a distance of about 1.2 km from the shore line. For marine growth studies, arrays of aluminum panels (150 x 100 xI mm) were exposed 1 m below the mean low tide level during the first week of September 1987. Triplicate panels were removed and replaced once in 2 months for analysing the composition of fouling, and removed once in 3 months for assessment of dry load. An additional set of panels was introduced in March 1988 to study biofouling during the successive 6 months. Panels were also exposed in the sheltered breakwaters of the harbour which has access to open sea only through a narrow channel. These panels were used for ascertaining the extent of biofouling load. In addition, scrape samples from the steel liners of CECRI platform up to a depth of 3 m from surface seawater, were also obtained period-