The article presents the history, the state of Mesolithic research and the most important Mesolithic sites in Slovenia. Knowledge about the Mesolithic in Slovenia is still poor, despite numerous newly discovered sites. This is due to inadequate excavation methods in the past and the lack of systematic research that would cover larger areas. Revision and wet sieving of part of the backdirt of the excavated Mesolithic layer of Mala Triglavca revealed a rich collection of microlithic tools, showing that, in addition to the Castelnovian, the Sauveterrian technological tradition is also represented at this site. Both Mesolithic phases are probably also represented in the Viktorjev spodmol. During underwater investigations of the Ljubija stream in the Ljubljansko barje (Ljubljana Marshes), in addition to resedimented stone and osseous tools, a human skull was found, which was radiocarbon dated to the Early Holocene. Thanks to amateur archaeologists, several open-air sites with stone artefacts were discovered in the mountains of the Upper Soča Valley. Based on stone artefacts collected during surface surveys and archaeological excavations, some of these sites can be assigned to the Sauveterrian, and the site of Leskovca II on the Leskovca alp may even belong to the Epigravettian. At the sites where faunal remains have been preserved, red deer and wild boar predominate among the hunting animals.