The terrestrial molluscan assemblages of 17 deciduous woodlands in north-east England are considered. Several of the sites contain nationally scarce species. To assess the relative value of the woods with respect to their molluscan fauna, a quality scoring system is presented, the assemblages are analysed and the species which characterise the best quality sites are discussed. These species include Vertigo substriata, Leiostyla anglica, Spermodea lamellata, Limax cinereoniger and Zenobiella subrufescens. The occurrence of these species is correlated with the presence of certain woodland flora, a relationship which could be used on a regional basis to predict the likely quality of molluscan assemblages in other woodlands. Some of the woodlands investigated are thought to be ancient and the extent to which data on molluscs concur with this view is considered.