The park of Oršić Castle in Gornja Bistra is a historically significant area and the park is also a park architecture monument. In this area, the vascular flora was studied and determined for the first time during the 2023 growing season. A total of 148 taxa in 51 families were recorded, of which Asteraceae (10.5%), Rosaceae (9.5%), Poaceae (7.4%) and Fabaceae (6.1%) are the most represented, while other families were recorded in a much lower proportion. Among the life forms, hemifriptophytes (H) are the most represented with 41.6% and phanerophytes (P) with 23.8%, while the proportion of the most abundant flora element is a combination of two flora elements artic and subatlantic (E, H) with 16.1%. Analyzes and inventories in the area revealed eleven invasive species (Acer negundo L., Amaranthus retroflexus L., Asclepias syriaca L., Conyza canadensis (L.) Cronquist, Erigeron annuus (L.) Desf., Parthenocissus tricuspidata (Siebold et Zucc.) Plachon, P. quinqefolia (L.) Planch, Phytolacca americana L., Reynoutria japonica Houtt., Robinia pseudoacacia L. i Veronica persica Poiret) and seven endangered species (from which is important to mention vulnerable (VU) are Ilex aquifolium L. and Taxus baccata L.). This is a historically significant area for which there is no previous documentation of plant material, and it is important to preserve and maintain it appropriately. The data collected can be used as a basis for further research and the restoration process that this park and castle are certainly expecting.