This paper illustrates the botanic heritage of Parche di Bilello, a site located in the municipality of Castelvetrano. The study area hosts several woodland fragments dominated by Olea europaea var. sylvestris, Quercus suber and Quercus ilex, respectively. According to historical data, these nuclei represent the last remnants of an open forestland which covered a much wider coastal area between Mazara del Vallo and Sciacca until the end of Middle Age. Phytosociological relevés were focused on these forest nuclei, probably the most representative of south-western Sicily, which correspond to three habitats included in the 92/43 EEC Directive (9320, 9330 and 9340, respectively) and represent the final stage of three different edaphic series. Wild olive forests probably dominated on sandy calcareous soils, holm oaks prevailed on steep calcareous and N-exposed slopes. In contrast, cork oaks mostly occurred on sandy subacid soils issuing from pedogenetic processes on palaeodunes. Moreover, field surveys allowed to list 331 vascular plant taxa. Among them, Linaria multicaulis subsp. humilis, Orobanche balsensis and Serapias orientalis subsp. siciliensis are new to Trapani Province. Detailed information on the current distribution and the synecology of several plant taxa of high biogeographic and conservation interest is also provided. The study site also hosts one habitat of priority interest (6220, i.e. xerophilous Mediterranean perennial grasslands and annual swards) and two species protected by international laws, i.e. the orchid Ophrys lunulata and the lichen Teloschistes chrysophthalmus. Considering the high value of its natural heritage, this territory deserves the adoption of more effective protection measures. For this reason the authors recommend its inclusion as a new Site of Community Interest within the Sicilian Natura 2000 network.