Recent studies substantiate the importance of the unsaturated zone in ground-water biodiversity of karst areas. Few investigations, however, have addressed the temporal changes in community composition in relation to water physico-chemical features. We provide information on the distribution pattern of the fauna in dripping water at spatial and temporal scales. This is related to variation in water chemistry and other environmental features in five caves within two hydrographic basins of the Pădurea Craiului Mountains (northwestern Romania). The analysis revealed no major pollution in the dripping water. The physico-chemical parameters varied within and between caves over one year. The dripping water fauna is heterogeneously distributed within and between the caves, containing a mixture of epigean and hypogean species. This emphasizes high microhabitat partition and also underlines the influence of physico-chemical parameters. The species composition among the two hydrographic basins was different. Crustaceans are the best represented in terms of both abundance and species richness. Six out of 15 crustacean species are endemic to the Pădurea Craiului Mountains and four are new to science. All these point to the importance of unsaturated karstic habitats as biodiversity hot spots in ground-water ecosystems.