Nematodes of the genus Anisakis are parasites that primarily invade marine mammals. In the life cycle, however, they also parasitize a lot of different, smaller organisms. In all these hosts , they cause a constant loss of energy, which affects the ir behavior and physiology, and the intensity depends on the amount of nematodes and, of course, the life stage (age) of the hosts. The aim of this b achelor thesi s is to study and present the characteristics of the species from the genus Anisakis their appearance, i.e. morphology, life cycle, presence in the Croatian part of the Adriatic sea and their impact on humans, primarily through the disease anisakiasis which they cause if they reach humans ( through intake of infected, raw or insufficiently thermally processed seafood such as, for example, undercooked squid, raw fish fillets or raw shrimp). It is worrying that outside scientific circles, not much is known about the problem of these nematodes and in many countries not enough precautions are taken . T his especially applies to countries with famous dishes made from raw fish or shrimps . In humans, the larva cannot develop to the adult egg producing stage (i.e. it cannot complete the life cycle) H umans are not the target destination of this parasite, but an accidental host. Even if the disease is ignored as a problem, it is clearly seen that the nematode parasitizes many economically i mportant and marketable fish such as tuna, hake or sea bream, which creates a problem in today's even more important economic activity fishery.