SummaryAfter almost two decades of research and evidence of brucellosis in marine mammals, it has become widely known that this disease is prevalent in marine mammals on a global scale. Positive animals have been found in the northern Atlantic, Mediterranean Sea and in the Arctic, including the Barents Sea. Infected or exposed animals have been detected along the Atlantic and Pacific coasts of North America, off the coasts of Peru, Australia, New Zealand, Hawaii, the Solomon Islands, and in the Antarctic Ocean. Brucellosis most commonly occurs in the harbour porpoise (Phocoena phocoena), followed by the striped dolphin (Stenella coeruleoalba), Atlantic white-sided dolphin (Lagenorhynchus acutus), bottlenose dolphin (Tursiops truncatus), shortbeaked common dolphin (Delphinus delphis) and minke whale (Balaenoptera acutorostrata). A positive serological reaction has been confirmed in 35 species of whales and 14 species of seals, two subspecies of sea otters, one species of freshwater otter and the polar bear. To date, brucellosis has been found in marine mammals in the Mediterranean Sea in Italy and Spain. The first research on brucellosis in dolphins in the Republic of Croatia began in 2015. Brucella sp. was isolated from the lymph node of a bottlenose dolphin found dead in the Poreč region. This was the first evidence of brucellosis in dolphins in the Adriatic Sea. The isolated sample was identified as Brucella ceti strain ST27, making this the first record of this strain in Europe, which may present a significant threat to human health.