This article describes an archaeological and dendrochronological research of a cistern discovered during the archaeological rescue excavations in the bailey of a medieval castle ruin at Tepenec, Central Moravia in 2008. The article characterizes the Tepenec site, describes the form of cistern, the archaeological research methodology as well as the methodology of dendrological analysis. The conclusion is devoted to the analysis of the dendrological dating results and how they benefit and expand our knowledge of the archaeology of the site.