Since skin basement membrane protein components are labile to conventional chemical fixation and since skin is not amenable to vibratome sectioning, frozen skin sections are routinely used for light microscopic immunohistochemical study of the skin basement membrane zone. However, inherent limitations of conventional frozen sections, including compromised morphology and a requirement for glass slidemounting, usually limit study to the light microscopic level. In the present study, we introduce the use of unfixed, free-floating cryostat sections to characterize immunolocalizations of selected basement membrane protein components at both the light and electron microscopy level. The new procedure employs free-floating cryostat sections that can be processed as routine tissue specimens and can be subjected to a variety of special staining procedures including immunohistochemistry. Especially useful is the ease of progressive processing of the same tissue specimen from light microscopy to electron microscopy.