A quantitative zonation study of intertidal molluscs in Malta shows that the Lewis (1964) zonation scheme is applicable to the microtidal coasts of the Mediterranean. The monotonous limestone substrates highlight the effects of wave action and exposure on molluscan distribution. Comparison with sublittoral transects reveals a distinct break between the intertidal and sublittoral fauna on the island. Although Malta has a small species pool, species richness at individual sites is high compared to other areas of the Mediterranean. Substrate type is suggested as a major control of species richness.