BaWO4 fishbone-like nanostructures with fourfold structural symmetry have been successfully grown in w/o microemulsion. The BaWO4 fishbone-like nanostructures have four rows of nanorods, epitaxially grown on the stem and perpendicular to the stem. The obtained samples are characterized by means of XRD, TEM, HRTEM, and SEM. It is found that the water content has a large influence on the size of the product and the molar ratio between cations and anions plays an important role in the morphology of the product. It is assumed that site-selective surfactant adsorption may be responsible for the formation of the BaWO4 fishbone-like nanostructures. (C) 2004 Elsevier Inc. All rights reserved.