Echinococcosis is a disease caused by tapeworms from the Echinococcus genus. The species that causes the majority of clinical cases among humans is Echinococcus granulosu, and the disease is called cystic echinococcosis. It is widely spread throughout the world and can be found in Croatia, also. Echinococcus granulosus can be found in nature among dogs who are the usual hosts, and among sheep who are the usual intermediate hosts. Humans are usually accidental intermediate hosts who acquire the disease via contact with dogs and dog feces. After infection, which is caused by ingesting parasite eggs, larvae are hatched inside the intestinal tract, and can subsequently reach any organ in the human body via bloodstream. Usually it reaches either the liver or lungs. A cyst is the intermediate larval stage, and is called metacestode. Echinococcal adult forms are found only in dogs' intestines, and are around half a centimetre in size. Most common symptoms that are found among patients are one or more cysts in the liver, which are often accompanied by hepatomegaly, jaundice, pain and discomfort in upper right abdomen. The second most common cyst site are the lungs, but cysts can be found in almost any other organ, such as ovaries, brain, heart or any other site. The disease is most commonly found after noticing cystic formations on imaging techniques such as ultrasound, CT, or MRI. In order to confirm the diagnosis multiple available microbiological methods are used, either direct or indirect. Direct methods include direct findings of parasitic larval elements in biopsy material, while indirect ones include numerous serological methods for specific echinococcal antibodies. Treatment depends on the stage in which the cyst is found and detected. Final treatment option, sometimes hardly manageable, is the surgical removal of the cyst. There is always the threat of cystic fluid spillage during the surgery, which can result in dissemination and serious allergic reactions. There is also the possibility of medicamentous treatment with antihelmintic drugs mebendazole and albendazole. The outcome of the disease is usually positive if it is treated properly. There is also another echinococcal species called Echinococcus multilocularis, which is lately becoming more common in Croatia, and it presents a much more serious clinical picture because its growth is not limited to only one cyst, but rather to multiple cysts which spread in the surrounding tissues and metastasize via bloodstream like malignant tumors. It causes a disease known as alveolar echinococcosis. Instead of dogs, the main host for Echinococcus multilocularis are foxes, while the intermediaries are rodents. Echinococcus multilocularis was first found in Croatia among foxes back in 2015. The first patient who developed the disease after being infected with this parasitosis was found two years later. The treatment of choice for this often deadly disease is chemotherapy, because by the time the symptoms start manifesting, surgical removal is no longer a viable option because multiple organs in the patient`s body have already been affected. The most common way to get infected is by eating small forest fruits from the forest ground that has been contaminated by parasitic eggs found in fox feces. In order to prevent echinococcal infections, we should implement harsher sheep population control and actively search for parasitic infections among them. People who are in the livestock business should avoid feeding dogs with suspicious intestines. In order to control infection among dogs, the most important step is to carry out periodic antihelmintic treatment of dogs to eliminate parasitic forms from their intestines. Another positive thing would be to implement preventive treatments of fox populations with antiparasitic drugs, in order to control the Echinococcus multilocularis species more efficiently.