Type XIV collagen belongs to the subclass of fibril-associated collagens with interrupted triple helices, which are composed of alternative triple helical and non-collagenous domains. Structural data show that these molecules interact with collagen fibrils and suggest that they might interact with cells. We have investigated the expression of type XIV collagen in bovine skin during development. Fetuses from 9 to 37 weeks were examined. Anti-type XIV collagen monoclonal antibody was produced, characterized, and used for immunofluorescence detection of the molecule. The localization of immunolabeling was analyzed by comparison with light and electron microscopic observations. In 9-week-old fetus, no type XIV collagen was found in the skin. From 19 weeks to birth, extensive immunofluorescence was observed on bundles of collagen fibrils in deep dermis. As shown by electron microscopy, this area exhibited bundles of collagen fibrils and cells with an abundant rough endoplasmic reticulum. In the upper dermis, a delicate fibrillar network of type XIV collagen was revealed by immunofluorescence around growing hair follicles at 19 and 24 weeks. Double labeling for type XIV collagen and fibronectin shows a more restricted pattern of expression of type XIV collagen in this area. The electron microscopic examination of skin of fetuses at these stages shows that the whole upper dermis is composed by a loose connective tissue containing scattered small bundles of collagen fibrils. Type XIV collagen was synthesized in the upper dermis between 24 weeks and birth. From this study, it appears that type XIV collagen expression is distinct from that of fibrillar collagens, at least during some developmental events. The prominent localization of type XIV collagen around growing hair follicles suggests a role for this molecule in epithelial-mesenchymal interactions.