Immunofluorescence microscopy of cultured cells often gives poor preservation of delicate structures. We have obtained dramatically improved results with a simple modification of a standard protocol. Cells growing on a coverslip are rapidly dehydrated in a cold organic solvent and then are rehydrated in a solution containing a homobifunctional crosslinker. The crosslinking reaction stabilizes cellular structures during subsequent incubation and wash steps, usually without compromising antigenicity. This method reproducibly yields high-quality images of endomembrane compartments and cytoskeletal elements.