The Middle Spotted Woodpecker Dendrocopos medius is a highly specialised woodpecker inhabiting mature deciduous forests. The presence of large mature oaks Quercus sp. is a very important factor determining the species' presence and distribution. In Slovenia it is more common in the eastern part, where it inhabits mainly lowland flood-plain oak forests. In other parts of the country it is more localised, as is the case in western Slovenia, where small isolated populations were recently discovered. In this paper we present the currently known observations of Middle Spotted Woodpecker in the Karst region (W Slovenia), the results of the first systematic survey and the first documented breeding of the species in this area. The survey was carried out on the 20 of March 2016 in the wooded hills between the villages of Senožeče and Veliko polje. Using playback method we recorded a total of 8 territorial woodpeckers, confirming our initial expectations about the species' abundance in that area. Breeding was also confirmed in the hills of Senožeče, an active nest-hole was found on 23 Apr 2017. On 18 May 2017 at least 3 juveniles successfully left the nest. Middle Spotted Woodpeckers have recently been observed also in other oak woodlands across the Karst and nearby areas, especially outside the breeding season. These areas include Lipica, Bazovica, the Brkini hills and the Gorica Karst. From summer 2016 onwards several observations of Middle Spotted Woodpeckers have been reported from Lipica, involving up to four different individuals. Repeated sightings in this area and the presence of suitable habitat suggest a probable breeding. The increased number of data in western Slovenia during the last decade might be a consequence of more frequent field visits by ornithologists. Moreover, the presence of the Middle Spotted Woodpecker in this part of the country might be linked to the gradual spreading of forests and the maturing of oak stands already present here. In the above-mentioned areas, further investigations and systematic censuses are therefore needed in the coming springs.