Pollution of the sea and the marine environment with ballast water belongs to the group of pollution whose source is on ships. On the one hand, ballast water intake and discharge are key actions for the ship's stability and safe navigation and on the other hand, ballast water poses one of the greatest threats to domestic ecosystems and domicile marine species and organisms, the question arises - how to regulate the issue of its amendment so that both parties are satisfied. By discharging ballast water into the destination port, foreign marine organisms are released into the coastal sea, which, through their rapid reproduction, disrupt the natural ecosystem and can cause the death of native marine species. In order to minimize such scenarios, the International Maritime Organization has been adopting a number of guidelines since the 1990s to prevent the introduction of foreign marine organisms by regulating its modification on the high seas. These guidelines were the predecessors of the most important international convention adopted in 2004, which deals exclusively with this issue - the International Convention for the Control and Management of Ships' Ballast Water and Sediments. As a state party to the said Convention, Republic of Croatia is obliged to adopt national laws, strategies and other ballast water management programs for the purpose of protecting the Adriatic Sea from invasive alien species. The Adriatic Sea is a shallow coastal sea, and therefore is in great danger of pollution through ballast water, so the Republic of Croatia must take all possible steps and activities to preserve its biodiversity and natural environment and domestic marine species and subspecies.