Paratuberculosis as well as Maedi/visna and Jaagsiekte came to Iceland in 1933 when 20 sheep of the Karakul breed were imported from Halle, Germany. At least 5 of these sheep were healthy carriers of paratuberculosis. In a matter of 16 years Paratuberculosis together with the other Karakul diseases (Maedi/visna and Jaagsiekte) almost ruined sheep farming, the main agricultural industry in Iceland. The first case of paratuberculosis in sheep was confirmed in 1938 and in cattle in 1944 on farms where the disease had been prevalent in sheep for years. The virulence in cattle appeared to be considerably lower than in sheep. Extensive measures were used to control the spread of paratuberculosis in sheep. Hundreds of kilometres of fences were put up and used together with natural geographic hindering to restrict the movement of sheep from infected areas. Serological and other immunological tests were furthermore used to detect and dispose of infected individuals. These measures were inadequate and the disease could not be eradicated. Extensive culling of sheep in endemic areas and restocking with healthy ones eradicated Maedi/Visna and Jaagsiekte but not paratuberculosis, whereas vaccination reduced mortality by 94%. Vaccination of sheep has been compulsory in Iceland since 1966 in endemic areas and as a result losses have been reduced considerably. Today serology is used on cattle to detect and control infection, and on sheep to control vaccination and screen for infection in non-endemic areas. The CF (complement fixation) test for paratuberculosis has been used until now, but recently we have started comparing the CF test with the CSL absorbed ELISA test. The parallel testing of sera with the CF test and the absorbed ELISA test is still going on and preliminary results will be presented.