Using immunocytochemistry at light- and electron-microscope levels, we studied the distribution of three monoclonal antibodies (AE1, AE2, AE3) specific for mammalian alpha-keratins in regenerating lizard epidermis. We also characterized the keratins expressed during this process by immunoblotting after electrophoretic separation. The AE1 antibody is localized in the basal and suprabasal layers of prescaling and scaling epidermis. During the first stages of scale neogenesis, the AE1 antibody also marks the differentiating oberhautchen and beta-layer, but it disappears from these layers as they mature. This antibody does not stain the prekeratinized and keratinized outermost layers in the hinge region. The AE2 antibody labels the superficial wound epidermis, prekeratinizing and keratinized beta- and alpha-layers, but not basal and suprabasal cells. The AE3 antibody labels all living and keratinized epidermal layers, although AE3 immunoreactivity decreases and disappears as the beta-layer matures. The ultrastructural study shows that the AE2 and AE3, but not the AE1, antibodies specifically label small electron-dense areas within the beta-layer, suggesting retention of alpha-keratins. In the stages of tail regeneration examined, immunoblotting with the three antibodies used for the immunolocalization gives a pattern similar to that of the normal epidermis, except distally, where the process of scale differentiation begins. In this region, in addition to the keratin forms discovered in the normal and in proximal regenerating epidermis, an intense low molecular weight band at 40-41 kDa, positive to all three antibodies, is clearly detectable. Furthermore, in the distal region AE1 and AE3 antibodies, but not the AE2, recognize a weak band at 77-78 kDa not present in the normal and proximal epidermis. The localization and the possible role of the different keratins in the regenerating epidermis is discussed.