We analysed assemblages of shells of land snails and small aquatic and wetland gastropods from a late Mesolithic-early Neolithic deposit in the cave of Pico Ramos (Basque Country). Shells were recovered by hand during excavation and all excavated deposit was processed by flotation, with a 250 μm mesh to recover floating material and a 1.0 mm mesh to recover the heavy fraction. The total assemblage comprised 5780 individuals (MNI) among 33 taxa, the sieved sub-assemblage having the highest proportions of these (2841 MNI in 31 taxa) and the hand-picked sub-assemblage the lowest (698 MNI in 11 taxa). Eleven taxa were absent from the flotation sub-assemblage, although the recovered MNI (2241; 39% of the total MNI) was high. The palaeoecological implications of the results are considered. Adult and large-sized juvenile shells of the edible land snail Cepaea nemoralis are abundant in the hand-picked sub-assemblage, but it is the absence of small-sized juvenile shells in the flotation and wet-sieved sub-assemblages that permits the inference that the species was collected for consumption. Wet sieving is therefore essential, both for interpreting hand-picked samples and in particular for the recovery of representative assemblages of land molluscs.