The availability of techniques that allow the quantitation of levels of ionized calcium within intact cells and synaptosomes, allows a new approach to understanding the events underlying neurotoxicity. By use of various pharmacological agents, it is possible to dissect out vulnerable loci within the cell that account for the increases in cytosolic calcium which accompany many neurotoxic events. The relation between calcium and cell death can now be more concisely addressed. This article gives examples of the types of questions that this new methodology can resolve. © 1988.