Five samples of clastic sediments from interior cave facies taken in three Slovenian relic caves (Trhlovca, Račiška pečina, and a cave in Črnotiče Quarry, Classical Karst, SW Slovenia) provided invertebrate fossil remains. Most of them belong to Oribatida but sparse individuals of Cladocera and insects were also identified. They represent the first pre-Quaternary invertebrate fossils found in sediments of continental temperate climate. The Pliocene/Pleistocene age of the sediments was determined by paleomagnetic dating chronologically calibrated by micromammal biostratigraphy. Invertebrate fossils could be validated as new proxy for the study of cave sediments due to their suitability for ecological and paleogeographic correlations in caves and outside the caves. They also bring additional information about cave formation and karst hydraulic regime in the area. Although the number of remains was very low, it is evidence that climatic conditions in caves allow a better preservation of fossil remains of some groups as compared to most of the surface habitats. This may open a new direction in the study of cave sediments.