Heavy metals which contaminate water due to ındustrialization cause a great deal of environmental pollution. In addition to that these metals threaten human health by accumulating in organismas which leave in rivers and seas and being used as nutriment.The aim of this resarch is to determine the mercury, lead and cadmium accumulation in scads (Trachurus trachurus ) caught in the Gulf of İzmit and near Tekirdag in the sea of Marmara. The resarch was carried out in April, May and June 1996. Fish sample analysed for mercury, lead and cadmium elements. Heavy metal contents of fish caught in the Gulf of İzmit were all higher than those of caught in Tekirdag . Avarege mercury contents were 0.316 ppm and 0.029 ppm in the Gulf of fishes and Tekirdag fishes respectively. Average lead contents were 0.269 ppm and 0.038 ppm in the Gulf fishes and Tekirdag fishes respectively. Average cadmium contents was 0.061 ppm in the Gulf fishes. No cadmium was determined in Tekirdağ fishes.