Spermathecal morphology is known to play an important role in postcopulatory sexual selection of many invertebrates. In helicid land snails, the spermatheca is subdivided into tubules, whose number is sometimes subject to a strong inter-individual variation. Significance of this variation for postcopulatory sexual selection is unknown, but it might be related to cryptic female choice. In the present work, we have investigated the fine multi-tubular structure of the sperm storage organ in Cantareus aspersus. We found between 3 and 13 tubules per individual in a single population, which represents a degree of variation rarely observed in helicid land snails.