Fascin-1 is an actin-bundling protein that contributes to the architecture and function of cell protrusions and microfilaments in cell adhesion, interactions and motility. Fascin-1 has been studied in cultured cells and by biophysical methods, but little is known about its distribution and functions in vertebrate development. As a first step to understanding the role of fascin-1 in embryogenesis, we have characterised the expression pattern of fascin-1 by in situ hybridisation on whole-mount and sectioned mouse embryos from embryonic day (E)8.0-E16.5. Fascin-1 was widely expressed throughout the embryo and the developing nervous system and mesenchymal tissues represented major sites of expression. Intense signals were observed in different regions of the brain, in the spinal cord and retina, and the cranial and dorsal root ganglia (DRG) appeared strongly positive. This neural expression remained strong throughout development. Fascin-1 was also present in the developing somites. High expression was detected in branchial arches and limb bud mesenchyme. At later stages, fascin-1 was expressed in different muscles of the face, skeletal muscles of the body, and in smooth muscle layers of several organs. Limb tendons appeared strongly positive. There was weak expression in heart ventricles. These results show that fascin-1 is principally expressed in neural and mesenchymal derivatives during embryonic development.