Ovaries were obtained from golden hamsters during proestrus and immersion-fixed for the immunocytochemical localization of albumin by the peroxidase-antiperoxidase method. Another group of ovaries were obtained from immature perfusion-fixed animals which had been stimulated for 48 or 96 h by gonadotrophins. Perfusion-fixed tissues were processed for the ultrastructural albumin localization using the protein A-gold technique. At the light microscopical level, albumin positive cells were seen more often in the corona radiata and the inner layer of the granulosa, but seldom in the outer layer. Thecal and interstitial gland cells revealed albumin reactivity as did the intra- and extravascular spaces. Using the electron microscope, enriched gold grains signalizing a positive albumin response were detected over lipid droplets of granulosal, thecal and luteal cells. Though labeled coated vesicles were absent, the following functional significance is proposed for this study: precursors of steroidogenesis or steroids may be transferred as ligands of albumin into or within the cell after a receptor-mediated uptake of the albumin ligand complex.