Recent data suggest that adrenocortical cells under pathological as well as under physiological conditions show neuroendocrine properties. Within the normal adrenal, this neuroendocrine differentiation seems to be restricted to cells of the zona glomerulosa and might be important for an autocrine regulation of adrenocortical function. In addition, such neuroendocrine differentiation is a common phenomenon in adrenocortical carcinomas and is therefore of clinical importance. In our studies, the expression of neuronal cell adhesion molecule (NCAM) could be shown in the zona glomerulosa of the normal human adrenal and in the human adrenocortical cell line NCI-H295 that also produces synaptophysin, a synaptic vesicle associated protein. In this chapter, data on neuroendocrine characteristics of adrenocortical cells are summarized and discussed.