In an attempt to collect more information about the features of the vernix caseosa (VC), a relatively unstudied material, some of the histochemical, ultrastructural, and immunological characteristics of VC cells have been investigated. Histochemistry and light microscopy was used to demonstrate the activity of acid and alkaline phosphatase in VC cells, enzymes with a marked increase in activity in the amniotic fluid toward term. Acid phosphatase activity was strongly present either as intracytoplasmic granules or as amorphous material between the cells; alkaline phosphatase activity was absolutely nonexistent. The ultrastructural morphology of the VC cells was analyzed by scanning and transmission electron microscopy (TEM). Significant differences can be demonstrated in the individual surface patterns of the VC keratinocytes. TEM showed irregularly flattened cells in various stages of keratinization. The ultrastructural findings confirm the dissimilarity, which exists between the individual VC cells. Finally, immunofluorescent staining tests of frozen VC smears showed that only immunoglobulin G conjugate gives strong positive reaction at the antigen sites of the VC cells. The special finding in this study is the polymorph appearance of the surface pattern and the cytoplasma structure of the VC cells, as well as the lack of uniform appearance of the acid phosphatase activity in and between the cells. All these suggest that the status of the individual VC cell is not similar in regard to their keratinization and desquamation activities.