ORGANIC-INORGANIC nanostructured composites provide a rich source of new materials(1-14) for a host of technological applications. For example, the incorporation of organic molecules in an inorganic lattice can toughen an otherwise brittle material(15-17), or be used to tailor its electronic properties(14), and cooperative interactions between organic and inorganic molecules are being used to generate a range of porous materials for separation and catalytic technologies(4-10). Here we describe the growth of stable semiconductor-organic superlattices based on cadmium sulphide and cadmium selenide, The template for the structures is provided by a liquid-crystalline phase formed from non-ionic organic amphiphiles, water and precursor ions for the inorganic semiconductor. Precipitation of the organic-inorganic solid takes place within the ordered environment of the mesophase, and both the symmetry and long-range order of the liquid crystal are preserved. We anticipate that materials of this type can be tailored, through the electronic properties of the organic amphiphiles, for photosynthetic and photocatalytic applications.