Drought represents a serious problem in the viticulture and winemaking sector of the Republic of Croatia, negatively affecting both yield reduction and grape quality. The Adriatic region of Croatia is particularly vulnerable to drought due to irregular rainfall patterns and extremely high temperatures; however, drought has become increasingly frequent in the continental part of the country as well. As a result of recurrent drought events, grape and wine producers in Croatia are experiencing significant economic losses. Drought also adversely affects the survival of natural populations of wild grapevine. Due to climate change, both the frequency and duration of drought periods are expected to increase. Most of the highly valued viticultural areas in Croatia are located in regions where the construction of irrigation systems is extremely difficult, primarily because of limited water resources. Therefore, in such areas, the cultivation of more drought-tolerant grapevine varieties represents almost the only viable strategy for mitigating stress. There is currently no scientific data on the drought tolerance of Croatian autochthonous grapevine varieties, although viticultural practice provides excellent examples of the adaptability of certain indigenous varieties under extremely dry site conditions. Precise definition of drought conditions and understanding of grapevine physiological responses to water deficit are crucial for identifying genes involved in these processes and for selecting more tolerant varieties. The aim of the project is to investigate the drought tolerance of Croatian autochthonous grapevine germplasm. Bioclimatic and production parameters of the main indigenous grapevine varieties and natural populations of wild grapevine in Croatia will be analyzed, and their level of drought tolerance will be assessed based on physiological, morphological, and genetic data. SSR and SNP markers will be analyzed. The project results will contribute to the development of sustainable viticulture.