The change in the numbers of synapse is of importance in various kinds of physiological and pathological processes. The numerical density is the structural parameter measuring up the numbers of the particles in the space. A new stereological technique, the disector technique, has been described to count the number of particles in a given volume of tissue. It is a technique for counting the number of arbitrary particles in 3-dimensional space using adjacent parallel sections at known distance apart. In this article also discussed is the software for computer assisted count of the synaptic numerical density based on the physical director technique with Visual Basic 4.0.