The objective of this article is to relate the emissions of tributyltin (TBT) used in antifouling paints for ships to the concentrations and the effects found in the marine environment. After a survey of the quantity of TBT used in antifouling paints for ships and the emissions in the marine environment, this article reviews the study on TBT in sediments and mussels along the Belgian coast and in the marine harbours and the imposex-survey with the dogwhelk Nucella lapillus . The results show that the concentration of TBT in the sediments of the Belgian harbours (especially Zeebrugge) are high and contrast with the lower concentration measured in the open sea. The imposex-survey confirms these higher concentrations. As a follow-up of the regulations of the Paris Commission and the CEE a new legislation for the use of organotin containing paints on ships smaller than 25 meters is in force in Belgium. On the understanding that this legislation is strictly applied, it can be expected that the TBT-concentrations in the marine environment will fall.