Babesia is a malaria-like, intraerythrocytic parasite with more than 100 different species. It is a zoonosis and some of the species are transmitted to humans by ticks and also as a possible transfusion-transmitted infection. In Sweden the disease has been well known in veterinary medicine for a long time, but only a few but severe cases have been published in humans during the last decades. Common symptoms from human Babesia infections (babesiosis) are fever, chills and myalgia and they vary from subclinical to potentially fatal among those with risk factors such as immunosuppression and splenectomy. In the U.S. more than 2,000 cases of babesiosis are found yearly and it is one of the most frequent fatal infections following blood transfusion. A study from southern Sweden has recently revealed a seroprevalence of 16% of Babesia antibodies among Borrelia-infected persons. These results indicate that there is a need to broaden awareness of Babesia in Sweden.