The Southern birch mouse, Sicista subtilis (Pallas, 1773), is one of the rarest and least known small mammal species in Europe. At present, the occurrence of its subspecies, the S. subtilis trizona (Frivaldszky, 1865), is confined to Hungary. The last living individual of this rare subspecies was caught in 1926. Prior to 2006, individuals were detected only from owl-pellets, but at fewer and fewer localities. After an 80 year hiatus in the records, the first living specimen was trapped on 21st June, 2006 in the Borsodi Mezőség (NE Hungary), at a location well known from previous skeletal records. In the same year, another 42 specimens were trapped. Recapture occurred only three times. The last three specimens were captured on 22nd September in 2006. So far S. subtilis trizona has occurred mainly in weed vegetation Carduetum acanthoidis and in its edge. These patches mostly border on abandoned plough-land vegetation (Convolvulo–Agropyretum repentis) dominated by annual grasses. The majority of the habitat had been ploughed a short time earlier (approx. 10–15 years), and barns and other farm-buildings occupying smaller part of it.