Metabolism of 14C-naphthalene was studied in aerobic and anaerobic marine sediments from the Mumbai coast, India using a continuous flow-through system for 5 weeks. There was no volatilisation of naphthalene from anaerobic sediment. Naphthalene underwent more extensive mineralization in aerobic sediment (31.6% of the applied activity) than in anaerobic sediment (5% of the applied activity). No metabolite of naphthalene was present in sediments at the end of the incubation period.