Research on permafrost in the Abisko area of northern Sweden date from the 1950s. A mean annual air temperature of -3 °C in the Abisko mountains (i.e. 1000 m a.s.l.) and -1 °C beyond the mountain area at an altitude of around 400 m suggests that both mountain and arctic permafrost occur there. Several geophysical surveys were performed by means of resistivity tomography (ERT) and electromagnetic mapping (EM). Wherever possible the geophysical survey results were calibrated by digging tests pits. The results show that permafrost occurs extensively in the mountain areas, especially those above 900 m a.s.l. and also sporadically at lower altitudes. At 400 m a.s.l. permafrost may be up to 30 m thick. Its thickness and extent are determined largely by the very variable local rock and soil conditions. Fossil permafrost is also likely to occur in this area.